Given an array containing n distinct numbers taken from 0, 1, 2, ..., n
, find the one that is missing from the array.
Example 1:
Input: [3,0,1] Output: 2
Example 2:
Input: [9,6,4,2,3,5,7,0,1] Output: 8
Note:
Your algorithm should run in linear runtime complexity. Could you implement it using only constant extra space complexity?
Solution 1:
class Solution { public int missingNumber(int[] nums) { int sum = 0; for (int i = 0; i <= nums.length; i++) { sum += i; } for (int num : nums) { sum -= num; } return sum; } }
Solution 2:
class Solution { public int missingNumber(int[] nums) { int res = nums.length; for (int i = 0; i< nums.length; i++) { res ^= i ^ nums[i]; } return res; } }