1125 咸鱼商店(“玲珑杯”线上赛 Round #15 河南专场)

题目链接：http://ifrog.cc/acm/problem/1125

思路就是二分最大值然后用O1背包判断就好了

代码如下：

#include<bits/stdc++.h>
using namespace std;

int s[1007], v[1007];
int dp[1000007];
int n, m, k;
bool judge(int x)
{
    memset(dp, 0, sizeof(dp));
    for(int i=1; i<=n; ++ i)
    {
        if(v[i] < x)
            continue;
        for(int j=m; j>=s[i]; -- j)
            dp[j] = max(dp[j], dp[j-s[i]] + v[i]);
    }
    return dp[m] >= k;
}

int main()
{
    while(scanf("%d%d%d", &n, &m, &k)!=EOF)
    {
        for(int i=1; i<=n; ++ i)
            scanf("%d%d", &s[i], &v[i]);

        if(judge(0) == false)
        {
            printf("-1\n");
            continue;
        }
        int b = 0, e = 1000000;
        while(b < e)
        {
            int mid = b + (e - b + 1) / 2;
            if(judge(mid))
                b = mid;
            else
                e = mid - 1;
        }
        printf("%d\n", b);
    }
    return 0;
}