268. Missing Number

 

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.

 

Example 1:

Input: nums = [3,0,1]

Output: 2

Explanation:

n = 3 since there are 3 numbers, so all numbers are in the range [0,3]. 2 is the missing number in the range since it does not appear in nums.

Example 2:

Input: nums = [0,1]

Output: 2

Explanation:

n = 2 since there are 2 numbers, so all numbers are in the range [0,2]. 2 is the missing number in the range since it does not appear in nums.

class Solution {

public int missingNumber(int[] nums) {

Map<Integer,Integer> result = new HashMap<>();

for(int num:nums){

result.put(num,result.getOrDefault(num,0)+1);

}

for(int i = 0;i<nums.length;i++){

int count = result.getOrDefault(i,0);

if(count == 0){

return i;

}

}

int n = result.size();

return n;

}

}