LeetCode--search-insert-position

题目描述

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

You may assume no duplicates in the array.

Here are few examples.

[1,3,5,6], 5 → 2

[1,3,5,6], 2 → 1

[1,3,5,6], 7 → 4

[1,3,5,6], 0 → 0
分析：二分查找，时间复杂度为O(logn)

class Solution {
public:
int searchInsert(int A[], int n, int target) {
        // 二分查找
        int low = 0;
        int high = n - 1;
        while (low <= high) {
            int mid = (low + high) / 2;
            if(A[mid] == target) return mid;
            else if(A[mid] < target) low = mid + 1;
            else high = mid - 1;
        }
        // 没找到返回low,即插入位置
        return low;
}
};