数据结构实验之查找四：二分查找

#include <iostream>
#include <algorithm>
#include <cstdio>
using namespace std;
int a[10000000+5];
int n, m, key;
int fin(int i, int j) {
    if(i>j) return -1;
    int mid=(i+j)/2;
    if(a[mid]==key) return mid-1;
    if(a[mid]>key)
        return fin(i,mid-1);
    return fin(mid+1,j);
}
int main()  {
    while(~scanf("%d %d", &n, &m)) {
        for(int i=1;i<=n;i++)
            scanf("%d", &a[i]);
        while(m--) {
            scanf("%d", &key);
            printf("%d\n", fin(1,n));
        }
    }
    return 0;
}