#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> ii;
typedef tuple<int,int,int> trinca;
const int INF = 1e9;
const int MAXN = 1e5 + 10;
const int MAXL = 17;
vector<ii> grafo[MAXN],adj[MAXN],arestas;
vector<trinca> Kruskal;
priority_queue<ii, vector<ii>, greater<ii> > pq;
int ancestral[MAXN][MAXL],liga[MAXN][MAXL],nivel[MAXN],processado[MAXN],dist[MAXN],n,m,dsu_parent[MAXN],dsu_weight[MAXN];
int find(int x){
if(x == dsu_parent[x]) return x;
return dsu_parent[x] = find(dsu_parent[x]);
}
void join(int x,int y){
x = find(x);
y = find(y);
if(dsu_weight[x] < dsu_weight[y]) swap(x,y);
dsu_parent[y] = x;
dsu_weight[x] += dsu_weight[y];
}
void dfs(int v,int p){
for(int i = 1;i<MAXL;i++){
int z = ancestral[v][i-1];
if(z != -1){
ancestral[v][i] = ancestral[z][i-1];
liga[v][i] = min(liga[v][i-1],liga[z][i-1]);
}
}
for(int i = 0;i<adj[v].size();i++){
int u = adj[v][i].first, w = adj[v][i].second;
if(u == p) continue;
nivel[u] = nivel[v] + 1;
ancestral[u][0] = v;
liga[u][0] = w;
dfs(u,v);
}
}
int LCA(int u,int v){
int ans = INF;
if(nivel[u] < nivel[v]) swap(u,v);
for(int i = MAXL - 1;i>=0;i--){
int z = ancestral[u][i],w = liga[u][i];
if(z != -1 && nivel[z] >= nivel[v]){
ans = min(ans,w);
u = z;
}
}
if(u == v) return ans;
for(int i = MAXL - 1;i>=0;i--){
if(ancestral[u][i] != ancestral[v][i] && ancestral[u][i] != -1 && ancestral[v][i] != -1){
ans = min(ans,liga[u][i]);
u = ancestral[u][i];
v = min(ans,liga[v][i]);
v = ancestral[v][i];
}
}
ans = min(ans, min(liga[v][0],liga[u][0]) );
return ans;
}
int main(){
memset(ancestral,-1,sizeof(ancestral));
scanf("%d %d",&n,&m);
for(int i = 1;i<=n;i++){
dsu_parent[i] = i;
dsu_weight[i] = 1;
}
for(int i = 1;i<=m;i++){
int u,v,w;
scanf("%d %d %d",&u,&v,&w);
grafo[u].push_back(ii(v,w));
grafo[v].push_back(ii(u,w));
arestas.push_back(ii(u,v));
}
int q;
scanf("%d",&q);
for(int i = 1;i<=q;i++){
int x;
scanf("%d",&x);
pq.push(ii(0,x));
}
while(!pq.empty()){
int d = pq.top().first, v = pq.top().second;
pq.pop();
if(processado[v]) continue;
processado[v] = 1;
dist[v] = d;
for(int i = 0;i<grafo[v].size();i++){
int u = grafo[v][i].first, w = grafo[v][i].second;
if(!processado[u]) pq.push(ii(d+w,u));
}
}
for(int i = 0;i<arestas.size();i++){
int u = arestas[i].first, v = arestas[i].second;
Kruskal.push_back(make_tuple(min(dist[u],dist[v]),u,v));
}
sort(Kruskal.begin(),Kruskal.end());
for(int i = (int)Kruskal.size()-1;i>=0;i--){
int u = get<1>(Kruskal[i]) , v = get<2>(Kruskal[i]), w = get<0>(Kruskal[i]);
if(find(u) != find(v)){
join(u,v);
adj[u].push_back(ii(v,w));
adj[v].push_back(ii(u,w));
}
}
dfs(1,-1);
scanf("%d",&q);
while(q--){
int u,v;
scanf("%d %d",&u,&v);
printf("%d\n",LCA(u,v));
}
return 0;
}
Compilation message
plan.cpp: In function 'void dfs(int, int)':
plan.cpp:31:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i = 0;i<adj[v].size();i++){
~^~~~~~~~~~~~~~
plan.cpp: In function 'int main()':
plan.cpp:89:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i = 0;i<grafo[v].size();i++){
~^~~~~~~~~~~~~~~~
plan.cpp:94:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i = 0;i<arestas.size();i++){
~^~~~~~~~~~~~~~~
plan.cpp:64:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d",&n,&m);
~~~~~^~~~~~~~~~~~~~~
plan.cpp:71:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d %d",&u,&v,&w);
~~~~~^~~~~~~~~~~~~~~~~~~~~
plan.cpp:77:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d",&q);
~~~~~^~~~~~~~~
plan.cpp:80:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d",&x);
~~~~~^~~~~~~~~
plan.cpp:108:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d",&q);
~~~~~^~~~~~~~~
plan.cpp:111:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
scanf("%d %d",&u,&v);
~~~~~^~~~~~~~~~~~~~~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
11 ms |
11668 KB |
Output is correct |
| 2 |
Correct |
13 ms |
11896 KB |
Output is correct |
| 3 |
Correct |
13 ms |
11908 KB |
Output is correct |
| 4 |
Correct |
12 ms |
11640 KB |
Output is correct |
| 5 |
Correct |
13 ms |
11912 KB |
Output is correct |
| 6 |
Correct |
13 ms |
11896 KB |
Output is correct |
| 7 |
Incorrect |
11 ms |
11640 KB |
Output isn't correct |
| 8 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
11 ms |
11668 KB |
Output is correct |
| 2 |
Correct |
13 ms |
11896 KB |
Output is correct |
| 3 |
Correct |
13 ms |
11908 KB |
Output is correct |
| 4 |
Correct |
12 ms |
11640 KB |
Output is correct |
| 5 |
Correct |
13 ms |
11912 KB |
Output is correct |
| 6 |
Correct |
13 ms |
11896 KB |
Output is correct |
| 7 |
Incorrect |
11 ms |
11640 KB |
Output isn't correct |
| 8 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
11 ms |
11768 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
292 ms |
35216 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
11 ms |
11668 KB |
Output is correct |
| 2 |
Correct |
13 ms |
11896 KB |
Output is correct |
| 3 |
Correct |
13 ms |
11908 KB |
Output is correct |
| 4 |
Correct |
12 ms |
11640 KB |
Output is correct |
| 5 |
Correct |
13 ms |
11912 KB |
Output is correct |
| 6 |
Correct |
13 ms |
11896 KB |
Output is correct |
| 7 |
Incorrect |
11 ms |
11640 KB |
Output isn't correct |
| 8 |
Halted |
0 ms |
0 KB |
- |
