287. Find the Duplicate Number
Given an array of integers nums containing n + 1 integers where each integer is in the range [1, n] inclusive.
There is only one duplicate number in nums, return this duplicate number.
Follow-ups:
- How can we prove that at least one duplicate number must exist in nums?
- Can you solve the problem without modifying the array nums?
- Can you solve the problem using only constant, O(1) extra space?
- Can you solve the problem with runtime complexity less than O(n2)?
Example 1:
Input: nums = [1,3,4,2,2]
Output: 2
Example 2:
Input: nums = [3,1,3,4,2]
Output: 3
Example 3:
Input: nums = [1,1]
Output: 1
Example 4:
Input: nums = [1,1,2]
Output: 1
Constraints:
- 2 <= n <= 3 * 104
- nums.length == n + 1
- 1 <= nums[i] <= n
- All the integers in nums appear only once except for precisely one integer which appears two or more times.
public int findDuplicate(int[] nums) {
while (nums[nums[0]]!=nums[0]) {
int temp = nums[0];
nums[0]=nums[nums[0]];
nums[temp]=temp;
}
return nums[0];
}