LeetCode # Array # Easy # 268. Missing Number

Given an array containing n distinct numbers taken from 0, 1, 2, ..., n, find the one that is missing from the array.

Question: Given an unordered array of length n and elements from 0 to n, if one is missing, which one is missing?

Ideas: /*My own ideas are too bad, and then I read the best solution, people are more popular than dead people*/ 

　　　The best solution: the cumulative sum from 0 to n is certain, find the sum of the existing array, and then subtract the two to get the missing element.

1 class Solution {
2     public int missingNumber(int[] nums) {
3         int sum = (nums.length + 1) * nums.length / 2, add = 0;//求和1
4         for(int i : nums) add += i;//求和2
5         return (sum - add);
6     }
7 }