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OI-codes/S2OJ/1698/1698.cpp

71 lines
1.3 KiB
C++

#include <iostream>
#include <algorithm>
#include <vector>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 1e6 + 5;
int t, n, m, q, cnt, block[N], color[N];
std::vector<int> g[N];
bool flag[N];
void dfs(int u, int f) {
block[u] = cnt;
for (int v : g[u]) {
if (color[v] != -1 && color[u] == color[v]) {
flag[cnt] = true;
} else if (color[v] == -1) {
color[v] = color[u] ^ 1;
dfs(v, u);
}
}
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> t >> n >> m;
for (int i = 1, u, v; i <= m; i++) {
cin >> u >> v;
g[u].emplace_back(v);
g[v].emplace_back(u);
}
std::fill_n(color, N, -1);
for (int i = 1; i <= n; i++) {
if (color[i] == -1) {
cnt++;
color[i] = 0;
dfs(i, 0);
}
}
cin >> q;
while (q--) {
int s, t;
cin >> s >> t;
if (s == t) {
cout << 0 << endl;
} else if (block[s] != block[t]) {
cout << -1 << endl;
} else if (flag[block[s]] || color[s] != color[t]) {
cout << 1 << endl;
} else {
cout << 2 << endl;
}
}
return 0;
}