287. 寻找重复数

class Solution {
    public int findDuplicate(int[] nums) {
        //快慢指针索引位置
        int slow=nums[0], fast=nums[nums[0]];

        //找到相遇结点
        while (nums[slow]!=nums[fast]){
            slow=nums[slow];
            fast=nums[nums[fast]];
        }


        //找到起始结点
        fast=0;
        while (slow!=fast){
            slow=nums[slow];
            fast=nums[fast];
        }

        return slow;
    }
}