[LeetCode]287. 寻找重复数

快慢指针算法

287. 寻找重复数

class Solution {
public:
    int findDuplicate(vector<int>& nums) {
        int fast=0,slow=0;
        while (true){
            fast=nums[nums[fast]];
            slow=nums[slow];
            if (slow==fast){
                //定位环入口
                fast=0;
                while (nums[slow]!=nums[fast]){
                    fast=nums[fast];
                    slow=nums[slow];
                }
                return nums[slow];
            }
        }
    }
};