Find Mode

• Problem Description

  
  Write a program to find the mode of a given list of integers. Mode of a number is defined as the number which is most frequently occurred. 
  For example: 
  
  L = {1,2,2,3} // Here mode is 2(most frequently occurred)
  
  It is possible that multiple answers are possible for a list. In that case print all possible answers in non-increasing order.
  
  Input:
  First Line of input contains an integer t representing the number of test cases, Where first line of each test case has an integers N - number of integers in list, Next line contains N integers.
  
  Output:
  print all the possible modes in non-increasing order.
  
  Constraints:
  1<=t<=100
  1<=N<100000
  1<=a[i]<=1000000
  

• Test Case 1

  
  Input (stdin)

  3
  
  5
  
  1 1 1 1 2
  
  7
  
  2 2 3 3 4 4 4
  
  10
  
  1 1 1 1 1 1 4 4 4 4
  
  

  Expected Output

  1 4 1

• Test Case 2

  
  Input (stdin)

  2
  
  3
  
  1 1 2
  
  7
  
  3 3 4 4 4 4 5
  
  

  Expected Output

  1 4

Solution

#include <stdio.h>

 

int main(){

int n,i,s,j;

scanf("%d", &n);

    for(i=0;i<n;i++)

    {

        scanf("%d",&s);

        int a[s],b[1000000],max=0;

        for(j=0;j<s;j++)

        {

            scanf("%d",&a[j]);

        }

        for(j=0;j<1000000;j++)

        {

            b[j] = 0;

        }

        

        for(j=0;j<s;j++)

        {

            if(b[a[j]] == 0)

            {

                b[a[j]] = 1;

            }

            else

            {

                b[a[j]] = b[a[j]] + 1;

            }

        }

        for(j=0;j<1000000;j++)

        {

            if(b[j] >= max)

            {

                max = b[j];

            }

        }

        for(j=1000000;j>0;j--)

        {

            if(b[j] == max)

            {

                printf("%d ",j);

            }

                

        }

        

    }

return 0;

}