0268-missing-number

268. Missing Number

Problem Description

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

Solution

public int missingNumber(int[] nums) {
    int n = nums.length;
    int sum = n * (n + 1) / 2;
    for (int i = 0; i < n; i++) {
        sum -= nums[i];
    }
    return sum;
}

Test

Compile with javac Solution.java and run with java -ea Solution.

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