STL BFS

/*

BFS algorithm in C++

*/
#include<stdio.h>
#define maxn 101

int Q[maxn];
int top ,back;
int Node, Edge;

char link[maxn][maxn];
char Fg[maxn];
int Path[maxn];

void Ini() {
int i, j;
for(i = 1; i<= Node; i++) {
for(j = 1; j<= Node; j++) {
link[i][j] = 0;
}
Path[i] = i;
Fg[i] = 0;
}
}

void Insert(int n) {
Q[back++] = n;
back %= maxn;
}

int Pop() {
int n = Q[top++];
top %= maxn;
return n;
}

int isEmpty() {
if(top == back) return 0;
return 1;
}

void PrintPath(int n) {
if(n == Path[n]) {
printf("%d",n);
return;
}
PrintPath(Path[n]);
printf(" %d",n);
}

int BFS(int s, int ter) {
int u, v, i;
Insert(s);
Fg[s] = 1;
while(isEmpty() == 1) {
v = Pop();
if(v == ter) {
PrintPath(v);
return 1;
}

for(i = 1; i<= Node; i++) {
if(link[v][i] == 1 && Fg[i] == 0)  {
Fg[i] = 1;
Insert(i);
Path[i] = v;
}
}
}
return -1;
}

void main() {
int i, u, v;
scanf("%d%d",&Node,&Edge);
Ini();
while(Edge--) {
scanf("%d%d",&u,&v);
link[u][v] = link[v][u] = 1;
}
scanf("%d%d",&u,&v);
BFS(u,v);
printf("\n");
}

/*
4 5
1 2
2 3
1 3
3 4
2 4
1 4
*/