Dating with girls

用二分查找。。

#include <stdio.h>
#include <stdlib.h>
#include <algorithm>
#include <string.h>
#include <istream>
using namespace std;

int A[100010],visit[100010];

//二分 
int find(int l, int r, int v)
{
    int mid;
    while (l <= r)
    {   
        //printf("****");
        mid = (l + r) / 2;
        if( A[mid] == v)
        return mid;
        else if ( v < A[mid])
        r = mid - 1;
        else
        l = mid + 1;
        
    }
    return 0;
}

int main( )
{ 
    int T, M, N, num, i, j=0, k, flag = 0;
    scanf("%d", &T);
    while (T--) {
        num = 0;
        flag = 0;
        j = 0;
        memset(visit, 0, sizeof(visit));
        memset(visit, 0, sizeof(A));
        scanf("%d%d", &M, &N);
        for (i = 0; i < M; i++)
          scanf("%d", &A[i]);
        sort(A, A+M);
        M = unique(&A[0],&A[0]+M) - &A[0]; //stl
        for(i = 0; i < M; i++) {
            if(!visit[i] && A[i] * 2 != N)
            j=find(i, M, N-A[i]);
            //printf("%d\n",j);
            if(j) {
            visit[j] = 1, num++;
            /* 如果用此for循环，则TLE 
            for (k = i; k < M; k++)
              if(A[k] == A[i] || A[j] == A[k] )
                  visit[k] = 1;
              else if ( A[k] > A[j] )
              break;
            */
            }
            
            if(A[i] * 2 == N)
            flag = 1;
            j=0;
        }
        num = 2 * num;
        if (flag) num++;
        printf("%d\n", num);
    }
    return 0;
}