二分查找

import java.util.*;

public class Solution {
/**
* 二分查找
* @param n int整型 数组长度
* @param v int整型 查找值
* @param a int整型一维数组 有序数组
* @return int整型
*/
public int upper_bound_ (int n, int v, int[] a) {
// write code here
if(a[0] >= v){
return 1;
}
if(a[n-1] < v){
return n+1;
}
int right = n - 1;
int left = 0;
int mid;
int index = 0;
while(left <= right){
mid = (right + left) /2;
if(a[mid] == v){
index = mid;
break;
}else if(a[mid] < v){
left = mid+1;
}else{
right = mid-1 ;
}

    }
    if(a[index] == v){
        while(index >= 0 && a[index] == v){
            index--;
        }
        return index + 2;
    }
    return left +1 ;


}

}