sicily：1155.Can I Post the letter

<span style="font-size:14px;">#include <iostream>
#include <queue>
using namespace std;

const int MAX_SIZE = 201;

int map[MAX_SIZE][MAX_SIZE];
bool visited[MAX_SIZE];
int n, m;
bool ans;

void init() {
ans = false;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++)
map[i][j] = -1;
map[i][i] = 0;
visited[i] = false;
}
}

void bfs(int s) {
visited[s] = true;
queue<int> q;
q.push(s);
while (!q.empty()) {
int u = q.front();
for (int i = 0; i < n; i++) {
if (map[u][i] > 0 && !visited[i]) {
if (i == n - 1) {
ans = true;
break;
}
visited[i] = true;
q.push(i);
}
}
q.pop();
}
}

int main() {
while (cin >> n && n) {
init();
cin >> m;
int u, v;
for (int i = 0; i < m; i++) {
cin >> u >> v;
map[u][v] = 1;
}
bfs(0);
if (ans) cout << "I can post the letter\n";
else cout << "I can't post the letter\n";
}
return 0;
}</span>