FZU-2216 The Longest Straight （二分枚举）

# include<iostream>
# include<cstdio>
# include<queue>
# include<vector>
# include<list>
# include<map>
# include<set>
# include<cstdlib>
# include<string>
# include<cstring>
# include<algorithm>
using namespace std;
# define LL long long

const int N=1000;
const int INF=1<<30;
const LL oo=1e15;
const double eps=1e-20;

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;
}