福建省赛--Problem E The Longest Straight(二分枚举)

# include<iostream>
# include<cstdio>
# include<cstring>
# include<algorithm>
using namespace std;

const int N=1000;

int n,m;
int sum[N*100+5];

int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d%d",&n,&m);
        memset(sum,0,sizeof(sum));
        int a,k=0;
        for(int i=0;i<n;++i){
            scanf("%d",&a);
            if(a) sum[a]=1;
            else ++k;
        }
        for(int i=1;i<=m;++i)
            sum[i]+=sum[i-1];
        int ans=0;
        for(int i=1;i<=m;++i){
            int l=i,r=m;
            while(l<=r){
                int x=(l+r)>>1;
                if(sum[x]-sum[i-1]+k>=x-i+1){
                    ans=max(ans,x-i+1);
                    l=x+1;
                }else{
                    r=x-1;
                }
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}