Codeforces Round #390 (Div. 2), problem: (B) Ilya and tic-tac-toe game Solution in C/C++

Codeforces Round #390 (Div. 2), problem: (B) Ilya and tic-tac-toe game Solution in C/C++

#include<stdio.h>
#include<stdlib.h>
typedef unsigned u;
char S[4][4];u x,o;
void chk(u r,u c,u dr,u dc,u s,u l)
{
	if(!(dr|dc))dr=-(dc=1);
	if(r>3||c>3){x=o=0;return;}
	if(l)x=o=0;
	if(S[r][c]=='x')++x;
	if(S[r][c]=='o')++o;
	if(s)chk(r+dr,c+dc,dr,dc,s-1,0);
	return;
}
int main()
{
	u i,j,k;
	scanf("%s%s%s%s",S[0],S[1],S[2],S[3]);
	for(i=-1;++i<4;)for(j=-1;++j<4;)for(k=-1;++k<4;)
	{
		chk(i,j,k>>1,k&1,2,1);
		if(x==2&&o==0){printf("YES\n");return 0;}
	}
	printf("NO\n");
	return 0;
}