【每日编程06】二分法

关于二分法小知识

class Solution {
    public int searchInsert(int[] nums, int target) {
        int left = 0, right = nums.length - 1;
        while(left <= right){
            int mid = left + (right - left) / 2;
            if(nums[mid] == target){
                return mid;
            }else if(nums[mid] > target){
                right = mid - 1;
            }else{
                left = mid + 1;
            }
        }
        return left;
    }
}

public class Solution extends VersionControl {
    public int firstBadVersion(int n) {
        int left = 1, right = n;
        while(left <= right){
            int mid = left + (right - left) / 2;
            if(isBadVersion(mid)){
                right = mid - 1;
            }else{
                left = mid + 1;
            }
        }
        return left;
    }
}

tips:

int mid = left + (right - left) / 2;很关键
如果是 int mid = (right + left) / 2;可能会发生整型溢出