Leetcode OJ: Search Insert Position

Search Insert Position

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

二分查找，需要注意的细节就是溢出问题，取中间数请保证加法不会造成溢出。见代码：

class Solution {
public:
    int searchInsert(int A[], int n, int target) {
        int begin = 0, end = n;
        int mid;
        while (begin < end) {
            // (begin + end) / 2是有溢出可能的
            mid = begin + ((end - begin) >> 1);
            if (A[mid] < target) {
                begin = mid + 1;
            } else if (A[mid] > target) {
                end = mid;
            } else {
                break;
            }
        }
        if (begin >= end) {
            return end;
        }
        return mid;
    }
};