为什么在poj上提交选C compile error选GCC runtime error？NO.1094哪位大神帮忙！该怎么处理

为什么在poj上提交选C compile error选GCC runtime error？NO.1094哪位大神帮忙！
代码如下：
#include<stdio.h>
#include<string.h>
int g[27][27];
int relation[900][2];
int go[27];
int in[27];
int used[27];
int sorted;
int orderchar[27];
int m, n;
void find(int x){
go[x]=1;
int i;
for(i=0; i<n; ++i)
if(g[x][i]&&!go[i])
find(i);
}
int topologic(int x){
int i, next=x, hasnext=1;
while(hasnext){
x=next;
orderchar[sorted]=x;
int zeros=0;
hasnext=0;
for(i=0; i<n; ++i)
if(g[x][i]) {
if((--in[i])==0) {next=i; ++zeros;}
++hasnext;
}
if(zeros>1) return 1;
++sorted;
}
if(sorted==n) return 0;
return 1;
}
int main(){
int l, r, i, j, k;
while(scanf("%d%d", &n, &m)&&n){
memset(g, 0, sizeof(g));
memset(in, 0, sizeof(in));
memset(relation, 0, sizeof(relation));
memset(used, 0, sizeof(used));
char s[5];
int finish=0;
for(i=0; i<m; ++i){
scanf("%s", s);
relation[i][0]=s[0]-'A';
relation[i][1]=s[2]-'A';
}
for(i=0; i<m; ++i){
memset(go, 0, sizeof(go));
l=relation[i][0]; r=relation[i][1];
g[l][r]=1; used[l]=1; used[r]=1;
find(r);
if(go[l]){
printf("Inconsistency found after %d relations.\n", i+1);
finish=1;
break;
}
++in[r];
sorted=0;
int zeros=0, enternum=0, location;
for(j=0; j<n; ++j) enternum+=used[j];
if(enternum<n) continue;
for(j=0; j<n; ++j)if(in[j]==0&&used[j]){location=j; ++zeros;}
if(zeros>1) continue;
int flag=topologic(location);
if(flag==0){
printf("Sorted sequence determined after %d relations: ", i+1);
for(j=0; j<n; ++j)
printf("%c", ((char)orderchar[j]+65));
printf(".\n");
finish=1;
break;
}
if(flag==1){
for(j=0; j<n; ++j)
for(k=0; k<n; ++k)
if(g[j][k]) ++in[k];
continue;
}
}
if(!finish) 
printf("Sorted sequence cannot be determined.\n");
}
return 0;
}


------解决方案--------------------
试选C++编译：

void find(int x){
 go[x]=1;
 int i; //c程序不能在这里定义变量。
 for(i=0; i<n; ++i)
 if(g[x][i]&&!go[i])
 find(i);
}