[LeetCode]Find the Duplicate Number

public class Solution {
public int findDuplicate(int[] nums) {
int slow = 0;
int fast = 0;
do {
slow = nums[slow];
fast = nums[nums[fast]];
} while (slow != fast);
slow = 0;
while (slow != fast) {
slow = nums[slow];
fast = nums[fast];
}
return slow;
}
}