简单01背包

优化后的，空间复杂度 O(n)

#include <iostream>
using namespace std;

int dfs(int *size, int *value, int C, int num) {
    int *dp = new int[C+1];
    for (int i = 0; i < C+1; i++)
        dp[i] = 0;

    for (int i = 1; i <= num; i++) {
        for (int j = C; j >= size[i]; j--)
            dp[j] = max(dp[j], dp[j-size[i]]+value[i]);
    }

    return dp[C];
}

int main() {
    int num, C;
    cin>>num>>C;

    int *size = new int[num+1];
    int *value = new int[num+1];

    for (int i = 1; i <= num; i++)
        cin >> size[i] >> value[i];

    cout << dfs(size, value, C, num) << endl;
    cin>>num;
    return 0;
}