編程演算法 - 背包問題(記憶化搜尋) 代碼(C)

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背包問題(記憶化搜尋) 代碼(C)

本文地址: http://blog.csdn.net/caroline_wendy

題目參考: http://blog.csdn.net/caroline_wendy/article/details/37912949

使用記憶化搜尋, 需要儲存每組的值, 下次不需要進行繼續迭代, 可以降低至時間複雜度O(nW).

代碼:

/* * main.cpp * *  Created on: 2014.7.17 *      Author: spike *//*eclipse cdt, gcc 4.8.1*/#include <stdio.h>#include <memory.h>#include <limits.h>#include <utility>#include <queue>#include <algorithm>using namespace std;class Program {static const int MAX_N = 100;int n=4, W=5;int w[MAX_N] = {2,1,3,2}, v[MAX_N]={3,2,4,2};int dp[MAX_N+1][MAX_N+1];int rec (int i, int j) {if (dp[i][j] >= 0) return dp[i][j];int res;if (i==n) {res = 0;} else if (j<w[i]) {res = rec(i+1, j);} else {res = max(rec(i+1,j), rec(i+1, j-w[i])+v[i] );}return dp[i][j] = res;}public:void solve() {memset(dp, -1, sizeof(dp));printf("result = %d\n", rec(0, W));}};int main(void){Program P;P.solve();    return 0;}

輸出:

result = 7