换钱的最少货币数
題目:
給定一個數組arr,arr中所有的值都為正數且不重復,每個值代表一種面值的貨幣,每種面值的貨幣有無數張,再給定一個整數aim代表要找的錢數,求組成aim的最少貨幣數。
"""暴力遞歸"""def minCoins(arr,aim):if arr == None or len(arr) == 0:return -1return process(arr,0,aim)def process(arr,i,rest):if i == len(arr):if rest == 0:return 0else:return -1k = 0res = -1while k*arr[i] < rest:next_ = process(arr,i+1,rest-k*arr[i])if next_ !=-1:if res == -1:res = next_ + kelse:res = min(res,next_ + k) k+=1return res"""動態規劃"""def minCoins1(arr, aim):import sysif arr == None or len(arr) == 0 or aim < 0:return -1row = len(arr)dp = [[sys.maxsize for i in range(aim+1)] for j in range(row)]for i in range(row):dp[i][0] = 0for j in range(1, aim+1):if j % arr[0] == 0:dp[0][j] = j // arr[0]for i in range(1, row):for j in range(1, aim+1):left = sys.maxsizeif j - arr[i] >= 0 and dp[i][j-arr[i]] != sys.maxsize:left = dp[i][j-arr[i]] + 1dp[i][j] = min(left, dp[i-1][j])return dp[row-1][aim] if dp[row-1][aim] != sys.maxsize else -1minCoins1([5,2,3],20)?
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