Missing Number

Easyarraymathbit-manipulation
Category: Bit Manipulation
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Approach

Missing Number

Problem Statement

Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.

Examples

Example 1:

Input: nums = [3,0,1]
Output: 2

Example 2:

Input: nums = [0,1]
Output: 2

Approach

Use XOR or sum formula. XOR all indices and values - pairs cancel out, leaving missing number.

Complexity

  • Time: O(n)
  • Space: O(1)

Solution

java
1class Solution {
2    public int missingNumber(int[] nums) {
3        int result = nums.length;
4        for (int i = 0; i < nums.length; i++) {
5            result ^= i ^ nums[i];
6        }
7        return result;
8    }
9}
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