#include<bits/stdc++.h>
using namespace std;
#define LOCAL
#ifndef LOCAL
#include "swap.h"
#endif // LOCAL
const int N = 1e5 + 10;
int n, m;
vector<pair<int, int>> ad[N];
vector<int> co;
void init(int N, int M, vector<int> U, vector<int> V, vector<int> W) {
n = N; m = M;
for (int i = 0; i < m; ++i) {
int u = U[i], v = V[i], w = W[i];
co.push_back(w);
ad[u].push_back({v, w});
ad[v].push_back({u, w});
}
sort(co.begin(), co.end());
co.resize(unique(co.begin(), co.end()) - co.begin());
}
bool dd[N];
int special;
bool dfs1(int u, int pre, int cw) {
if (u == special) return 1;
bool ret = 0;
for (auto duck : ad[u]) {
int v, w; tie(v, w) = duck;
if (v == pre || w > cw) continue;
if (!dd[v]) {
dd[v] = 1;
ret |= dfs1(v, u, cw);
}
}
return ret;
}
bool dfs2(int u, int pre, int cw) {
int cnt = bool(pre);
bool ret = 0;
map<int, int> d;
for (auto duck : ad[u]) {
int v, w; tie(v, w) = duck;
if (v == pre || w > cw) continue;
if (dd[v] && !d[v]) return 1;
if (!dd[v]) {
dd[v] = d[v] = 1;
cnt += 1;
ret |= dfs2(v, u, cw);
}
}
return (cnt > 2 || ret);
}
int getMinimumFuelCapacity(int X, int Y) {
int l = 0, r = co.size() - 1;
int answer = -1;
special = Y;
while (l <= r) {
int mid = l + r >> 1;
bool ret = 1;
memset(dd, 0, sizeof dd); ret &= dfs1(X, 0, co[mid]);
memset(dd, 0, sizeof dd); ret &= dfs2(X, 0, co[mid]);
if (ret) r = mid - 1, answer = co[mid];
else l = mid + 1;
}
return answer;
}
#ifdef LOCAL
int32_t main() {
cin.tie(0)->sync_with_stdio(0);
if (fopen("duck.inp", "r")) {
freopen("duck.inp", "r", stdin);
freopen("duck.out", "w", stdout);
}
int n, m; cin >> n >> m;
vector<int> U(m), V(m), W(m);
for (int i = 0; i < m; ++i) cin >> U[i] >> V[i] >> W[i];
init(n, m, U, V, W);
int q; cin >> q;
for (int i = 1; i <= q; ++i) {
int X, Y; cin >> X >> Y;
cout << getMinimumFuelCapacity(X, Y) << '\n';
}
}
#endif // LOCAL
Compilation message
swap.cpp: In function 'bool dfs2(int, int, int)':
swap.cpp:56:20: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
56 | dd[v] = d[v] = 1;
swap.cpp: In function 'int getMinimumFuelCapacity(int, int)':
swap.cpp:71:17: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
71 | int mid = l + r >> 1;
| ~~^~~
swap.cpp: In function 'int32_t main()':
swap.cpp:89:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
89 | freopen("duck.inp", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
swap.cpp:90:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
90 | freopen("duck.out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/ld: /tmp/cc2yZt9u.o: in function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/cciiYefv.o:swap.cpp:(.text.startup+0x0): first defined here
collect2: error: ld returned 1 exit status
