find first repeating name in multiple names entered by the user - c

Question

There was a breakfast organised by social workers. There were many people in line to get the food packet. Find out first person who reappeared in line for food packet quickly.
Given
Adam, Binny, Sohail, Krishna , Mayank, Sohail, Adam
The output should be:
Sohail
I am unable to solve this in c language.
Please can somebody explain what to do?
This is my code:
#include<stdio.h>
int main()
{
int n,i,j;
char str[20][20];
scanf("%d",&n);
for(i=0;i<n;i++)
{
scanf("%s",&str[i]);
}
for(i=0;i<n;i++){
for(j=i+1;j<n;j++){
if(str[i]==str[j]){
printf("%s\n",str[i]);
return 0;
}
}
}
return 0;
}
I am getting nothing in output.

Answer 1

It can give you some directions:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct PersonInfo
{
char *name;
int number;
} person_info;
void check(person_info arr[], size_t size);
int main()
{
char *arr_debug[20] = {"Adam", "Binny", "Sohail", "Krishna", "Mayank", "Sohail", "Adam"};
int i = 0;
person_info arr[7];
size_t size = sizeof(arr)/sizeof(arr[0]);
person_info temp;
for (i = 0; i < size; i++) {
// scanf("%s", temp.name);
temp.name = arr_debug[i];
temp.number = i + 1; // start counting from 1
arr[i] = temp;
}
check(arr, size);
return 0;
}
void check(person_info arr[], size_t size) {
char *temp_name;
int nums[size]; // filled with 0s
int num = 0;
for (int i = 0; i < size; i++) {
for (int j = 0; j < size; j++) {
if (strcmp(arr[i].name, arr[j].name) == 0 && arr[i].number < arr[j].number) {
nums[num] = arr[j].number;
num++;
//store the number of the person
}
}
}
//find the earliest occurence
int earliest = nums[0];
for (int i = 1; i < size; i++) {
if (earliest > nums[i] && nums[i] != 0) {
earliest = nums[i];
}
}
//find the name associated to the number
for (int i = 0; i < size; i++) {
if (arr[i].number == earliest) {
temp_name = arr[i].name;
printf("%s \n", temp_name);
}
}
}