Given an array nums containing n + 1 integers where each integer is between 1 and n (inclusive), prove that at least one duplicate number must exist. Assume that there is only one duplicate number, find the duplicate one.
Example 1:
Input: [1,3,4,2,2]
Output: 2
Example 2:
Input: [3,1,3,4,2]
Output: 3
Note:
- You must not modify the array (assume the array is read only).
- You must use only constant, O(1) extra space.
- Your runtime complexity should be less than O(n2).
- There is only one duplicate number in the array, but it could be repeated more than once.
According to the conditions, sorting or new Set/Object creation is not allowed.
/**
* @param {number[]} nums
* @return {number}
*/
var findDuplicate = function(nums) {
let i = 0,
j = i + 1
while (i < nums.length - 1) {
// if two pointers have same number return the number
if (nums[i] === nums[j]) return nums[i]
// move j along
else if (j < nums.length - 1) {
j++
}
// move i along & reset j position
else if (j == nums.length - 1) {
i++
j = i + 1
}
}
}
- Time Complexity: Min
O(N)
MaxO(N^2)
- Space Complexity: O(1)
- To Be Updated