35.Search Insert Position

思路：

• 直接遍历数组。复杂度为\(O(n)\)。

class Solution {
public:
    int searchInsert(vector<int>& nums, int target) {
        if(target < nums[0]) return 0;
        if(target > nums[nums.size()-1]) return nums.size();
        for(int i = 0; i < nums.size(); i++){
            if(nums[i] == target) return i;
            if(nums[i] > target) return i;
        }
    }
};

• 利用二分查找，注意最后利用mid找插入位置。复杂度为\(O(log(n))\)。

class Solution {
public:
    int searchInsert(vector<int>& nums, int target) {
        int len = nums.size();
        int lo = 0,hi = len-1;
        int flag = 0;
        int pos = -1;
        int mid = 0;
        
        while(lo <= hi){
            mid = (hi + lo)/ 2;
            if(nums[mid] == target){
                flag = 1;
                pos = mid;
                break;
            }
            else if(nums[mid] < target){
                lo = mid+1;
            }
            else hi = mid -1;
        }
        
        if(flag) return pos;
        else if(nums[mid] > target) return mid;
        else  return mid+1;
    }
};