Search Insert Position [LEETCODE]

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

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First , code a O(n) solution, see if it exceeds time limit:

class Solution {
public:
    int searchInsert(int A[], int n, int target) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int i = 0;
        for(; i < n; i++) {
            if(target <= A[i]) {
                return i;
            }
        }
        return i;
    }
};

Submission Result: Accepted 

OK, this problem does not seem have much expectation in me...

But I still want to challenge myself with it.

So I tried a O(lgn) solution using binary search.

class Solution {
public:
    int searchInsert(int A[], int n, int target) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int left = 0;
        int right = n - 1;
        int mid = (left + right) / 2;
        while(1){
            if(target == A[mid]) {
                return mid;    
            }
            if(target > A[mid]){
                //find in right sector
                left = mid + 1;
            }
            else if(target < A[mid]){
                //find in left sector
                right = mid - 1;
            }
            if(left > right){
                if(target > A[mid]){
                    return mid + 1;
                } else {
                    return mid;
                }
            }
            mid = (left + right) / 2;
        }
    }
};

OK AC again. CON!!!