HUT-XXXX 周正虎的难题 二分

这题直接二分就可以了，注意下二分的返回值，以后都最好手动模拟一下。

代码如下：

#include <cstdlib>

#include <cstdio>

#include <cstring>

#include <algorithm>

using namespace std;



typedef long long int Int64;



Int64 N, M, seq[1000005];



Int64 sum(Int64 h)

{

    Int64 ret = 0;

    for (int i = 1; i <= N; ++i) {

        if (seq[i] > h) {

            ret += (seq[i] - h);

        }

    }

    return ret;

}



Int64 bsearch(Int64 l, Int64 r)

{

    Int64 mid, tot;

    while (l <= r) {

        mid = (l + r) >> 1;

        tot = sum(mid); 

        if (tot > M) {

            l = mid + 1;

        }

        else if (tot < M) {

            r = mid - 1;

        }

        else return mid;

    }

    return r;

}



int main()

{ 

    Int64 Max;

    while (scanf("%I64d %I64d", &N, &M) == 2) {

        Max = -1;

        for (int i = 1; i <= N; ++i) {

            scanf("%I64d", &seq[i]);

            Max = max(Max, seq[i]);

        }

        printf("%I64d\n", bsearch(0, Max));

    }

    return 0;

}