#include "highway.h"
#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define mp make_pair
using namespace std;
const int maxn = 100100;
int n, m;
vector<int>w;
vector<int>gs[maxn];
vector<pair<int,int> > g[maxn];
vector<int>gt[maxn];
int dist[maxn][2], parent[maxn][2];
int pind[maxn];
bool visited[maxn];
ll dista;
map<pair<int,int>, int> ind;
int type[maxn];
vector<pair<int,int> > sta, stb;
bool important[maxn];
void bfs(int u, int v) {
visited[u] = visited[v] = true;
queue<pair<int,int> > q;
type[u] = 0;
type[v] = 1;
q.push(mp(u, 0));
q.push(mp(v, 1));
pind[u] = pind[v] = -1;
while(!q.empty()) {
int curr = q.front().first;
int currtype = q.front().second;
q.pop();
for(auto i:g[curr]) {
int ni = i.first;
int nind = i.second;
if(visited[ni]) continue;
visited[ni] = true;
type[ni] = currtype;
pind[ni] = nind;
q.push(mp(ni, currtype));
}
}
}
int solve(int root, int d) {
// build bfs tree
memset(visited,false,sizeof(visited));
//memset(parent,-1,sizeof(parent));
vector<int>v, v2, vind;
queue<int>q;
q.push(root);
visited[root] = true;
parent[root][d] = -1;
while(!q.empty()) {
int curr = q.front();
q.pop();
v.pb(parent[curr][d]);
v2.pb(curr);
vind.pb(pind[curr]);
if(pind[curr] != -1)
important[pind[curr]] = true;
for(auto i:gs[curr]) {
if(!visited[i] && type[i] == type[curr]) {
visited[i] = true;
parent[i][d] = curr;
dist[i][d] = dist[curr][d] + 1;
q.push(i);
}
}
}
if(v.size() == 1) return v2[0];
// perform binary search
vector<int>w(m, 0);
for(int i=0;i<v.size();i++) {
if(v[i] == -1) continue; // root
int cind = vind[i];
w[cind] = 1;
}
int li = 0, ri = v.size() - 1;
while(li < ri) {
int mid = (li + ri) / 2;
// all before mid put them as low cost and other as high cost
for(int i=0;i<=mid;i++) {
if(v[i] == -1) continue; // root
int cind = vind[i];
w[cind] = 0;
}
for(int i=0;i<m;i++) {
if(!important[i]) w[i] = 1;
}
ll cdist = ask(w);
for(int i=0;i<=mid;i++) {
if(v[i] == -1) continue; // root
int cind = vind[i];
w[cind] = 1;
}
for(int i=0;i<m;i++) {
if(!important[i]) w[i] = 0;
}
if(cdist == dista) {
ri = mid;
}
else {
li = mid + 1;
}
}
for(int i=0;i<v.size();i++) {
if(v[i] == -1) continue; // root
int cind = vind[i];
w[cind] = 0;
}
return v2[li];
}
void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
n = N; m = U.size();
int li=0, ri=m-1;
for(int i=0;i<m;i++) {
//ind[mp(U[i], V[i])] = ind[mp(V[i], U[i])] = i;
gs[U[i]].pb(V[i]);
gs[V[i]].pb(U[i]);
g[U[i]].pb(mp(V[i], i));
g[V[i]].pb(mp(U[i], i));
w.pb(0);
}
dista = ask(w);
while(li<ri) {
int mid = (li+ri)/2;
for(int i=li;i<=mid;i++) {
w[i] = 1;
}
ll distb = ask(w);
for(int i=li;i<=mid;i++) {
w[i] = 0;
}
if(dista == distb) {
li = mid + 1;
}
else {
ri = mid;
}
}
int x = li;
int u = U[x], v = V[x];
important[x] = true;
//cout<<u<<" "<<v<<"\n";
bfs(u, v);
//preprocess();
//memset(visited,false,sizeof(visited));
//cout<<"Ans: "<<xx<<" "<<yy<<"\n";
answer(solve(u, 0), solve(v, 1));
}
Compilation message
highway.cpp: In function 'int solve(int, int)':
highway.cpp:92:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i=0;i<v.size();i++) {
~^~~~~~~~~
highway.cpp:133:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i=0;i<v.size();i++) {
~^~~~~~~~~
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
8 ms |
7392 KB |
Output is incorrect: {s, t} is wrong. |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
10 ms |
7544 KB |
Output is correct |
2 |
Incorrect |
32 ms |
8800 KB |
Output is incorrect: {s, t} is wrong. |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
21 ms |
8736 KB |
Output is correct |
2 |
Correct |
50 ms |
9852 KB |
Output is correct |
3 |
Correct |
68 ms |
11220 KB |
Output is correct |
4 |
Correct |
197 ms |
18280 KB |
Output is correct |
5 |
Correct |
185 ms |
18260 KB |
Output is correct |
6 |
Correct |
190 ms |
18508 KB |
Output is correct |
7 |
Correct |
193 ms |
18928 KB |
Output is correct |
8 |
Correct |
158 ms |
18048 KB |
Output is correct |
9 |
Correct |
208 ms |
18764 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
10 ms |
7544 KB |
Output is incorrect: {s, t} is wrong. |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
37 ms |
8968 KB |
Output is incorrect: {s, t} is wrong. |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Incorrect |
37 ms |
8748 KB |
Output is incorrect: {s, t} is wrong. |
2 |
Halted |
0 ms |
0 KB |
- |