炫酷镜子
https://ac.nowcoder.com/acm/contest/331/I
C++版本一
std
題解：
注意到固定轉(zhuǎn)向的鏡子沒有辦法匯聚，也就沒有辦法卡掉模擬光線。
直接模擬即可，或者使用并查集或者記憶化搜索也可。
時(shí)間復(fù)雜度O(NM)
#include <bits/stdc++.h>using namespace std;//為了更好的擴(kuò)展性，這里提供一份記憶化搜索題解const int mn = 505;int n, m; char s[mn][mn];const int dx[] = {1, -1, 0, 0}; const int dy[] = {0, 0, 1, -1};int d[mn][mn][4]; // up down left rightint dp(int x, int y, int from) {int &ans = d[x][y][from];if (ans) return ans;if (x == n + 1) return y;if (y <= 0 || y > m || x <= 0) return -1;if (s[x][y] == '\\') {if (from == 0) ans = dp(x, y + 1, 2);if (from == 1) ans = dp(x, y - 1, 3);if (from == 2) ans = dp(x + 1, y, 0);if (from == 3) ans = dp(x - 1, y, 1);}if (s[x][y] == '/') {if (from == 0) ans = dp(x, y - 1, 3);if (from == 1) ans = dp(x, y + 1, 2);if (from == 2) ans = dp(x - 1, y, 1);if (from == 3) ans = dp(x + 1, y, 0);}if (s[x][y] == '.') ans = dp(x + dx[from], y + dy[from], from);return ans; }int main() {scanf("%d%d", &n, &m);for (int i = 1; i <= n; i++) scanf("%s", s[i] + 1);for (int i = 1; i <= m; i++) printf("%d\n", dp(1, i, 0));return 0; }C++版本二
DFS
/* *@Author: STZG *@Language: C++ */ #include <bits/stdc++.h> #include<iostream> #include<algorithm> #include<cstdlib> #include<cstring> #include<cstdio> #include<string> #include<vector> #include<bitset> #include<queue> #include<deque> #include<stack> #include<cmath> #include<list> #include<map> #include<set> //#define DEBUG #define RI register int using namespace std; typedef long long ll; //typedef __int128 lll; const int N=500+10; const int MOD=1e9+7; const double PI = acos(-1.0); const double EXP = 1E-8; const int INF = 0x3f3f3f3f; int t,n,m,k,q; int ans,cnt,flag,temp; int dir[][2]={-1,0,0,1,1,0,0,-1}; char str[N][N];int find(int flag,int x,int y,int c){cout<<x<<" "<<y<<endl;if(x<1||y<1||y>m)return -1;if(x>n)return y;if(c>n*m)return -1;if(str[x][y]=='\\'){if(flag==0)flag=3;else if(flag==1)flag=2;else if(flag==2)flag=1;else if(flag==3)flag=0;}if(str[x][y]=='/'){if(flag==0)flag=1;else if(flag==1)flag=0;else if(flag==2)flag=3;else if(flag==3)flag=2;}return find(flag,x+dir[flag][0],y+dir[flag][1],c+1); } int main() { #ifdef DEBUGfreopen("input.in", "r", stdin);//freopen("output.out", "w", stdout); #endifscanf("%d%d",&n,&m);//scanf("%d",&t);//while(t--){}for(int i=1;i<=n;i++)scanf("%s",str[i]+1);for(int i=1;i<=m;i++)cout << find(2,1,i,1) << endl;//cout << "Hello world!" << endl;return 0; }?
總結(jié)
