POJ 2488 A Knight's Journey

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stack>
using namespace std;
int c;
int n,p,q;
int start_x,start_y;
int total_count=0;
bool flag=false;
bool visited[30][30]={false};
typedef struct Node {
int x,y;
}Node;
Node nodes[8]={{-2,-1},{-2,1},{-1,-2},{-1,2},{1,-2},{1,2},{2,-1},{2,1}};
typedef struct Father {
int x,y;
}Father;
Father father[30][30]={{-1,-1}};
void init()
{
flag=false;
memset(visited,false,sizeof(visited));
}
bool check(int x,int y)
{
if(!(0<=x&&x<p&&0<=y&&y<q))    return false;
return true;
}
void out_result(int a,int b)
{
stack<int> S;
int x=a,y=b;
printf("Scenario #%d:\n",c);
S.push(b);
S.push(a);
while(!(father[x][y].x==-1&&father[x][y].y==-1)) {
S.push(father[x][y].y);
S.push(father[x][y].x);
int X=father[x][y].x,Y=father[x][y].y;
x=X;
y=Y;
}
while(!S.empty()) {
putchar(S.top()+'A');
S.pop();
putchar(S.top()+'1');
S.pop();
}
putchar('\n');
putchar('\n');
}
void dfs(int x,int y,int count)
{
if(flag)    return;
if(count==total_count) {
out_result(x,y);
flag=true;
return ;
}
int i;
for(i=0;i<8;i++) {
if(check(x+nodes[i].x,y+nodes[i].y)&&!visited[x+nodes[i].x][y+nodes[i].y]) {
visited[x+nodes[i].x][y+nodes[i].y]=true;
father[x+nodes[i].x][y+nodes[i].y].x=x;
father[x+nodes[i].x][y+nodes[i].y].y=y;
dfs(x+nodes[i].x,y+nodes[i].y,count+1);
visited[x+nodes[i].x][y+nodes[i].y]=false;
}
}
}
int main()
{
scanf("%d",&n);
for(c=1;c<=n;c++) {
here:        scanf("%d%d",&q,&p);
int i,j;
total_count=p*q;
for(i=0;i<p;i++) {
for(j=0;j<q;j++) {
visited[i][j]=true;
father[i][j].x=-1;
father[i][j].y=-1;
start_x=i;
start_y=j;
dfs(start_x,start_y,1);
if(flag) {
init();
c++;
if(c<=n)
goto here;
else return 0;
}
init();
}
}
if(!flag) {
printf("Scenario #%d:\n",c);
printf("impossible\n");
putchar('\n');
}
}
return 0;
}