poj1276(多重背包)

#include <cstdio>
#include <cstring>

const int MAXN = 1e5+10;

bool dp[MAXN];
int num[MAXN], val[MAXN];
int l, n;

int main()
{
    while (~scanf("%d%d", &l, &n)) {
        int sum = 0;
        for (int i = 1; i <= n; ++i) {
            scanf("%d%d", num+i, val+i);
            sum += num[i] * val[i];
        }
        if (sum <= l) {
            printf("%d\n", sum);
            continue;
        }
        memset(dp, false, sizeof dp);
        dp[0] = true;
        for (int i = 1; i <= n; ++i) {
            for (int j = l; j >= 0; --j) {
                if (true == dp[j]) {
                    for (int k = 1; k <= num[i]; ++k) {
                        if (j + k * val[i] > l)
                            continue;
                        dp[j + k * val[i]] = true;
                    }
                }
            }
        }
        int i;
        for (i = l; i >= 1; --i)
            if (true == dp[i])
                break;
        printf("%d\n", i);
    }
    return 0;
}