645.FindErrorNums.cs

// 645. Set Mismatch

// You have a set of integers s, which originally contains all the numbers from 1 to n. Unfortunately, due to some error, one of the numbers in s got duplicated to another number in the set, which results in repetition of one number and loss of another number.

// You are given an integer array nums representing the data status of this set after the error.

// Find the number that occurs twice and the number that is missing and return them in the form of an array.

 

// Example 1:

// Input: nums = [1,2,2,4]
// Output: [2,3]


public class Solution {
    public int[] FindErrorNums(int[] nums) {
        int[] freq = new int[nums.Length+1];
        int[] result = new int[2];
        for(int i=0;i<nums.Length;i++)
            freq[nums[i]]++;
        for(int i=1;i<freq.Length;i++){
            if(freq[i]>1)
                result[0] = i;
            else if(freq[i]==0)
                result[1] = i;
        }
        return result;
    }
}