hdu4889Scary Path Finding Algorithm【构造】搞坏spfa-slf 2014多校联合
Problem Description Fackyyj loves the challenge phase in TwosigmaCrap(TC). One day, he meet a task asking him to find shortest path from vertex 1 to vertex n, in a graph with at most n vertices and m edges. (1 ≤ n ≤ 100,0 ≤ m ≤ n(n-1))
Fackyyj solved this problem at first glance, after that he opened someone's submission, spotted the following code:
long long spfa_slf() {
int n,m;
cin >> n >> m;
vector<pair<int,int> > edges[111];
for(int i = 0;i < m;i++) {
int x,y,w;
cin >> x >> y >> w;
edges[x].push_back(make_pair(y,w));
}
deque<int> q;
vector<long long> dist(n+1, ~0ULL>>1);
vector<bool> inQueue(n+1, false);
dist[1] = 0; q.push_back(1); inQueue[1] = true;
int doge = 0;
while(!q.empty()) {
int x = q.front(); q.pop_front();
if(doge++ > C) {
puts("doge");
return 233;
}
for(vector<pair<int,int> >::iterator it = edges[x].begin();
it != edges[x].end();++it) {
int y = it->first;
int w = it->second;
if(dist[y] > dist[x] + w) {
dist[y] = dist[x] + w;
if(!inQueue[y]) {
inQueue[y] = true;
if(!q.empty() && dist[y] > dist[q.front()])
q.push_back(y);
else
q.push_front(y);
}
}
}
inQueue[x] = false;
}
return dist[n];
}
Fackyyj's face lit up with an evil smile. He immediately clicked button "Challenge!", but due to a hard disk failure, all of his test case generators were lost! Fackyyj had no interest on recreating his precise generators, so he asked you to write one. The generator should be able to generate a test case with at most 100 vertices, and it must be able to fail the above code, i.e. let the above code print "doge". It should NOT contain any negative-cost loop.
For those guys who doesn't know C++, Fackyyj explain the general idea of the above algorithm by the following psuedo-code:
Input Input contains several test cases, please process till EOF.
For each test case, there will be a single line containing an integer C. It is the constant C in the above code. (C <= 23333333)
Output For each test case, on the first line, print two integers, n and m, indicating the number of vertices and the number of edges of your graph. Next m lines, on each line print x y w, means there is a road from x to y, cost w.
1 ≤ n ≤ 100,0 ≤ m ≤ n(n-1),|w| < 231. Note that your output shouldn't contain any negative-cost loop.
Sample Input 1
Sample Output 4 3 1 2 1 2 3 1 3 4 1
Author Fudan University
Source 2014 Multi-University Training Contest 3
題意：給出spfa_slf優(yōu)化的代碼，要你寫示例使得代碼壞掉==
做法：首先應該分析這堆代碼，每次拿出隊首元素并彈出，查找隊首元素相連的點，與現在的隊首元素比較，距離比隊首元素大的放到隊尾，小的放到隊首。每個元素跳出的次數大于給定值的時候輸出”doge“。這個SLF其實對于有些數據來說是可以做到優(yōu)化的，因為可以認為距離較小的點可能更新的點比較多。
造一組數據模擬一下這個過程：（就是正解）
61 90
1 2 0
3 4 0
5 6 0
7 8 0
9 10 0
11 12 0
13 14 0
15 16 0
17 18 0
19 20 0
21 22 0
23 24 0
25 26 0
27 28 0
29 30 0
31 32 0
33 34 0
35 36 0
37 38 0
39 40 0
41 42 0
43 44 0
45 46 0
47 48 0
49 50 0
51 52 0
53 54 0
55 56 0
57 58 0
59 60 0
2 3 -1073741824
4 5 -536870912
6 7 -268435456
8 9 -134217728
10 11 -67108864
12 13 -33554432
14 15 -16777216
16 17 -8388608
18 19 -4194304
20 21 -2097152
22 23 -1048576
24 25 -524288
26 27 -262144
28 29 -131072
30 31 -65536
32 33 -32768
34 35 -16384
36 37 -8192
38 39 -4096
40 41 -2048
42 43 -1024
44 45 -512
46 47 -256
48 49 -128
50 51 -64
52 53 -32
54 55 -16
56 57 -8
58 59 -4
60 61 -2
1 3 -536870912
3 5 -268435456
5 7 -134217728
7 9 -67108864
9 11 -33554432
11 13 -16777216
13 15 -8388608
15 17 -4194304
17 19 -2097152
19 21 -1048576
21 23 -524288
23 25 -262144
25 27 -131072
27 29 -65536
29 31 -32768
31 33 -16384
33 35 -8192
35 37 -4096
37 39 -2048
39 41 -1024
41 43 -512
43 45 -256
45 47 -128
47 49 -64
49 51 -32
51 53 -16
53 55 -8
55 57 -4
57 59 -2
59 61 -1
（注意加邊的順序！）
然后按著題意的操作就出來如下的結果，每行的表示當前隊列中的點
front:1
? 2
? 3? 2
front:3
? 4? 2
? 5? 4? 2
front:5
? 6? 4? 2
? 7? 6? 4? 2
front:7
? 8? 6? 4? 2
? 9? 8? 6? 4? 2
front:9
?10? 8? 6? 4? 2
?11 10? 8? 6? 4? 2
front:11
?12 10? 8? 6? 4? 2
?13 12 10? 8? 6? 4? 2
front:13
?14 12 10? 8? 6? 4? 2
?15 14 12 10? 8? 6? 4? 2
front:15
?16 14 12 10? 8? 6? 4? 2
?17 16 14 12 10? 8? 6? 4? 2
front:17
?18 16 14 12 10? 8? 6? 4? 2
?19 18 16 14 12 10? 8? 6? 4? 2
front:19
?20 18 16 14 12 10? 8? 6? 4? 2
?21 20 18 16 14 12 10? 8? 6? 4? 2
front:21
?22 20 18 16 14 12 10? 8? 6? 4? 2
?23 22 20 18 16 14 12 10? 8? 6? 4? 2
front:23
?24 22 20 18 16 14 12 10? 8? 6? 4? 2
?25 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:25
?26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?27 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:27
?28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?29 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:29
?30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?31 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:31
?32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?33 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:33
?34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?35 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:35
?36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?37 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:37
?38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?39 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:39
?40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?41 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:41
?42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?43 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:43
?44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?45 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:45
?46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?47 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:47
?48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?49 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:49
?50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?51 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:51
?52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?53 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:53
?54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?55 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:55
?56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?57 56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:57
?58 56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?59 58 56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 58 56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 58 56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
front:60
?61 58 56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
front:58
?59 56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
front:60
?61 56 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
front:56
?57 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:57
?58 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?59 58 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 58 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 58 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
front:60
?61 58 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
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?59 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
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?61 54 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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front:54
?55 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?56 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?57 56 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:57
?58 56 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?59 58 56 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 58 56 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 58 56 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
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?61 58 56 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
front:58
?59 56 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 56 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 56 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
front:60
?61 56 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
front:56
?57 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:57
?58 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?59 58 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 58 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 58 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
front:60
?61 58 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
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?59 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
front:60
?61 52 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
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?53 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?55 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:55
?56 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?57 56 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:57
?58 56 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?59 58 56 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 58 56 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 58 56 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
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?61 58 56 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?59 56 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?60 56 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 56 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
front:60
?61 56 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
front:56
?57 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:57
?58 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?59 58 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 58 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 58 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
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?61 58 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
front:58
?59 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
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?61 54 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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front:54
?55 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:55
?56 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?57 56 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:57
?58 56 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?59 58 56 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 58 56 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 58 56 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
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?61 58 56 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?59 56 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?60 56 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 56 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
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?61 56 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?57 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?58 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?59 58 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 58 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 58 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?61 58 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?59 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?60 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?61 50 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?51 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?53 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?55 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?56 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?57 56 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:57
?58 56 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?59 58 56 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 58 56 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 58 56 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
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?61 58 56 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?59 56 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?60 56 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 56 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
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?61 56 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?57 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?58 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?59 58 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 58 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 58 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?61 58 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?59 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?60 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:61
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?61 54 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?55 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?56 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?57 56 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?58 56 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?59 58 56 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
front:59
?60 58 56 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 58 56 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?61 58 56 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?59 56 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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?60 56 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
?61 60 56 52 48 46 44 42 40 38 36 34 32 30 28 26 24 22 20 18 16 14 12 10? 8? 6? 4? 2
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分析一下結果：從開頭開始看每次操作相當于取出的如果是奇數，就把與其相連的偶數放到隊首，然后把下一個奇數放到這個偶數前面。這樣每次取出的隊首都是奇數。把所有奇數遍歷過一遍之后，就輪到從大到小的偶數了，偶數只連著比他大一的奇數，所以這些奇數又一次入隊列了。換言之f(i)>2*f(i+2) ，那么這個復雜度就很高很高~~
再從結果分析建邊方式：之所以要先寫權值是0的邊，因為我需要先讓偶數的點入隊列啊，不然+2的奇數點入隊列之后偶數點就進不去了，導致+2的奇數點無法再次進入隊列！
再分析思路：題中想要每個點進入隊列的次數多一些，那么就要盡可能多入隊列
#include <iostream> #include<cstdio> using namespace std; int a; int main() {// freopen("cin.txt","w",stdout);while(~scanf("%d",&a)){int t=30;printf("%d %d\n",t*2+1,t*3);for(int i=0;i<t;i++)printf("%d %d %d\n",i*2+1,2+i*2,0);for(int i=0;i<t;i++)printf("%d %d %d\n",2*i+1,2*i+3,-(1<<t-i-1));for(int i=0;i<t;i++)printf("%d %d %d\n",2*i+2,2*i+3,-(1<<t-i));}return 0; } //#include <algorithm> //#include <iostream> //#include <cstring> //#include <cstdio> //#include <deque> //#include<vector> //using namespace std; //long long spfa_slf() { // int n,m; // cin >> n >> m; // // vector<pair<int,int> > edges[111]; // for(int i = 0;i < m;i++) { // int x,y,w; // cin >> x >> y >> w; // edges[x].push_back(make_pair(y,w)); // } // // deque<int> q; // vector<long long> dist(n+1, ~0ULL>>1); // vector<bool> inQueue(n+1, false); // dist[1] = 0; q.push_back(1); inQueue[1] = true; // // int doge = 0; // while(!q.empty()) { // int x = q.front(); q.pop_front(); // printf("front:%d\n",x); // if(doge++ > 200) { // puts("doge"); // return 233; // } // for(vector<pair<int,int> >::iterator it = edges[x].begin();it != edges[x].end();++it) { // int y = it->first; // int w = it->second; // if(dist[y] > dist[x] + w) { // dist[y] = dist[x] + w; // if(!inQueue[y]) { // inQueue[y] = true; // if(!q.empty() && dist[y] > dist[q.front()]) // q.push_back(y); // else // q.push_front(y); // } // for(int i=0;i<q.size();i++)printf("%3d",q[i]);puts(""); // // for(int i=0;i<q.size();i++)printf("%3d",dist[q[i]]);puts(""); // } // } // inQueue[x] = false; // // } // return dist[n]; //} //int main() //{ // freopen("cin.txt","r",stdin); // spfa_slf(); // return 0; //}
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