sicily 1342 （0/1背包问题）

//首次接触背包问题，理解起来还是有点吃力！需要多练习！ 

#include "iostream"#include "cmath"using namespace std;int total[26][300010];int main(){int N, m;while (cin >> N >> m){int *price = new int[m+1];int *degree = new int[m+1];for (int i = 0; i <= m; i++)for (int j = 0; j <= N; j++)total[i][j] = 0;for (int i = 1; i <= m; i++)cin >> price[i] >> degree[i];int ans = 0;for (int i = 1; i <= m; i++)for (int j = 1; j <= N; j++){if (price[i] <= j){if (total[i-1][j] < total[i-1][j-price[i]] + price[i] * degree[i])//动态规划的公式！要理解透，熟悉运用！{total[i][j] = total[i-1][j-price[i]] + price[i] * degree[i];    ans = max(total[i][j], ans);}else{total[i][j] = total[i-1][j];ans = max(total[i][j], ans);}}else {total[i][j] = total[i-1][j];ans = max(total[i][j], ans);}}cout << ans << endl;}}