题目
代码部分（1ms 98.87%）
class Solution {
public int findDuplicate(int[] nums) {
if(nums.length == 1) return 0;
int slow = nums[0];
int fast = nums[slow];
while(fast != slow){
slow = nums[slow];
fast = nums[nums[fast]];
}
fast = 0;
while(fast != slow){
slow = nums[slow];
fast = nums[fast];
}
return slow;
}
}
