This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> llp;
typedef pair<int, int> ii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;
typedef vector<vii> vvii;
#define mp(x, y) make_pair(x, y)
#define pb(x) push_back(x)
int N, M;
int Z, D, SV1, SV2;
vvi edges;
int Ddists[200000], Zdists[200000];
int Dparents[200000];
void dijsktra(int *dists, int s) {
set<ii> S;
for (int i = 0; i < N; i++) {
if (i == s) {
dists[i] = 0;
S.insert(mp(dists[i], i));
continue;
}
dists[i] = (int)1e9;
S.insert(mp(dists[i], i));
}
while ( ! S.empty() ) {
ii x = *S.begin();
S.erase(S.begin());
for (int i = 0; i < edges[x.second].size(); i++) {
if (dists[x.second] + 1 < dists[edges[x.second][i]]) {
S.erase(mp(dists[edges[x.second][i]], edges[x.second][i]));
dists[edges[x.second][i]] = dists[x.second] + 1;
if (s == D) Dparents[edges[x.second][i]] = x.second;
S.insert(mp(dists[edges[x.second][i]], edges[x.second][i]));
}
}
}
}
int main(int argc, char **argv) {
//freopen("input", "r", stdin);
//freopen("output", "w", stdout);
scanf("%d%d", &N, &M);
scanf("%d%d%d%d", &Z, &D, &SV1, &SV2);
Z--; D--; SV1--; SV2--;
edges.resize(N);
for (int i = 0; i < M; i++) {
int a, b; scanf("%d%d", &a, &b);
a--, b--;
edges[a].pb(b);
edges[b].pb(a);
}
Dparents[D] = -1;
dijsktra(Ddists, D);
dijsktra(Zdists, Z);
int best1 = -1;
int best2 = -1;
int x = Dparents[SV1];
while (x != -1) {
//if (x) cerr << x << endl;
int fark = Ddists[x] - Zdists[x];
best1 = max(best1, fark);
x = Dparents[x];
}
x = Dparents[SV2];
while (x != -1) {
int fark = Ddists[x] - Zdists[x];
best2 = max(best2, fark);
x = Dparents[x];
}
int sv1 = Ddists[SV1] - Zdists[SV1];
int sv2 = Ddists[SV2] - Zdists[SV2];
int minsv = min(sv1, sv2);
int ans = -1;
ans = max(ans, min(best1, best2));
ans = max(ans, minsv);
//if (Dparents[SV1] == SV2) best1 = max(best1, Ddists[SV1] - Zdists[SV1] - 2);
//if (Dparents[SV2] == SV1) best2 = max(best2, Ddists[SV2] - Zdists[SV2] - 2);
//int ans = min(best1, best2);
if (Dparents[SV1] != SV2 && Dparents[SV2] != SV1 && min(best1, best2) != ans) ans = (ans!=-1?ans-1:-1);
printf("%d\n", (ans!=-1?ans:-1));
return 0;
}
Compilation message (stderr)
007.cpp: In function 'void dijsktra(int*, int)':
007.cpp:33:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for (int i = 0; i < edges[x.second].size(); i++) {
^
007.cpp: In function 'int main(int, char**)':
007.cpp:49:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d%d", &N, &M);
^
007.cpp:50:39: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d%d%d%d", &Z, &D, &SV1, &SV2);
^
007.cpp:54:34: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
int a, b; scanf("%d%d", &a, &b);
^
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