Convert this code in C with different logic

#include<bits stdc++.h="">

using namespace std;

#define MAX_CHAR 256

int findRepeatFirst(char* s)
{

	int p = -1, i, k;

	int hash[MAX_CHAR] = { 0 };


	int pos[MAX_CHAR];

	for (i = 0; i < strlen(s); i++) {
		k = (int)s[i];
		if (hash[k] == 0) {
			hash[k]++;
			pos[k] = i;
		} else if (hash[k] == 1)
			hash[k]++;
	}

	for (i = 0; i < MAX_CHAR; i++) {
		if (hash[i] == 2) {
			if (p == -1)
				p = pos[i];
			else if (p > pos[i])
				p = pos[i];
		}
	}

	return p;
}


int main()
{
	char str[MAX_CHAR];
	cin>>str;
	int pos = findRepeatFirst(str);
	if (pos == -1)
		cout << "YES"<<endl;
 else
   cout << "no"<<endl;
 return="" 0;
}

#include<bits stdc++.h>

using namespace std;

#define MAX_CHAR 256

int findRepeatFirst(char* s)
{

	int p = -1, i, k;

	int hash[MAX_CHAR] = { 0 };


	int pos[MAX_CHAR];

	for (i = 0; i < strlen(s); i++) {
		k = (int)s[i];
		if (hash[k] == 0) {
			hash[k]++;
			pos[k] = i;
		} else if (hash[k] == 1)
			hash[k]++;
	}

	for (i = 0; i < MAX_CHAR; i++) {
		if (hash[i] == 2) {
			if (p == -1)
				p = pos[i];
			else if (p > pos[i])
				p = pos[i];
		}
	}

	return p;
}


int main()
{
	char str[MAX_CHAR];
	cin>>str;
	int pos = findRepeatFirst(str);
	if (pos == -1)
		cout << "YES"<