• Source 
    1. /*
    2. ********************************************
    3. This code only for beginners.  Please, Don't Copy Past
    4. ********************************************
    5. */
    6.  
    7. // Letter Frequency 
    8.  
    9. #include<stdio.h>
    10. int main()
    11. {
    12.  
    13.     char str[500],dummy;
    14.     int big;   
    15.     int t;
    16.  
    17.     scanf("%d%c",&t,&dummy);
    18.     while(t--){                // what an idea
    19. 		gets(str);
    20.         int i,arr[27]={0};   
    21.  
    22.         big =0;
    23.         for(i=0;str[i]!=NULL;i++){
    24.  
    25.             if(str[i]>=65 && str[i]<=90)
    26.                 str[i]=str[i]+32;
    27.  
    28.             if(str[i]=='a')
    29.                 arr[1]++;
    30.             else if(str[i]=='b')
    31.                 arr[2]++;
    32.             else if(str[i]=='c')
    33.                 arr[3]++;
    34.             else if(str[i]=='d')
    35.                 arr[4]++;
    36.             else if(str[i]=='e')
    37.                 arr[5]++;
    38.             else if(str[i]=='f')
    39.                 arr[6]++;
    40.             else if(str[i]=='g')
    41.                 arr[7]++;
    42.             else if(str[i]=='h')
    43.                 arr[8]++;
    44.             else if(str[i]=='i')
    45.                 arr[9]++;
    46.             else if(str[i]=='j')
    47.                 arr[10]++;
    48.             else if(str[i]=='k')
    49.                 arr[11]++;
    50.             else if(str[i]=='l')
    51.                 arr[12]++;
    52.             else if(str[i]=='m')
    53.                 arr[13]++;
    54.             else if(str[i]=='n')
    55.                 arr[14]++;
    56.             else if(str[i]=='o')
    57.                 arr[15]++;
    58.             else if(str[i]=='p')
    59.                 arr[16]++;
    60.             else if(str[i]=='q')
    61.                 arr[17]++;
    62.             else if(str[i]=='r')
    63.                 arr[18]++;
    64.             else if(str[i]=='s')
    65.                 arr[19]++;
    66.             else if(str[i]=='t')
    67.                 arr[20]++;
    68.             else if(str[i]=='u')
    69.                 arr[21]++;
    70.             else if(str[i]=='v')
    71.                 arr[22]++;
    72.             else if(str[i]=='w')
    73.                 arr[23]++;
    74.             else if(str[i]=='x')
    75.                 arr[24]++;
    76.             else if(str[i]=='y')
    77.                 arr[25]++;
    78.             else if(str[i]=='z')
    79.                 arr[26]++;
    80.         }
    81.  
    82.         for(i=1;i<27;i++){
    83.             if(arr[i]>big)
    84.                 big=arr[i];
    85.             //    printf("hi ");
    86.  
    87.         }
    88.  
    89.         for(i=1;i<27;i++){
    90.             if(big==arr[i])
    91.                 printf("%c",i+96);        //printting the letter of higher frequency
    92.         }
    93.         printf("\n");
    94.     }
    95. return 0;
    96. }