#include<bits/stdc++.h>
using namespace std ;
const int maxl = 22 ;
const int maxn = 2e5 + 5 ;
int n, q, m ;
int pai[maxn], vis[maxn], sz[maxn], tab[maxl][maxn], nivel[maxn], mx_t[maxl][maxn] ;
vector<pair<int,int>> grafo[maxn] ;
struct DSU{
int find(int a){(a == pai[a] ? a : pai[a] = find(pai[a])) ; }
void join(int a, int b){
a = find(a), b = find(b) ;
if(a == b) return ;
if(sz[a] > sz[b]) swap(a, b) ;
sz[b] += sz[a] ; pai[a] = b ;
}
} dsu ;
void dfs(int v, int p){
vis[v] = 1 ;
tab[0][v] = p ;
for(auto a : grafo[v]){
if(a.first == p || vis[a.first]) continue ;
mx_t[0][a.first] = a.second ;
nivel[a.first] = nivel[v] + 1 ;
dfs(a.first, v) ;
}
}
int lca(int a, int b){
if(nivel[a] > nivel[b]) swap(a, b) ;
int ans = 0 ;
for(int i = maxl - 1 ; i >= 0 ; i--){
if(tab[i][b] != -1 && nivel[tab[i][b]] >= nivel[a]){
ans = max(ans, mx_t[i][b]) ;
b = tab[i][b] ;
}
}
if(a == b) return ans ;
for(int i = maxl - 1 ; i >= 0 ; i--){
if(tab[i][a] != -1 && tab[i][b] != -1 && tab[i][a] != tab[i][b]){
ans = max({ans, mx_t[i][a], mx_t[i][b]}) ;
a = tab[i][a], b = tab[i][b] ;
}
}
return max({ans, mx_t[0][a], mx_t[0][b]}) ;
}
int main(){
ios_base::sync_with_stdio(false) ; cin.tie(NULL) ;
cin >> n >> m >> q ;
for(int i = 1 ; i <= n ; i++) pai[i] = i, sz[i] = 1 ;
for(int i = m ; i >= 1 ; i--){
for(int j = i + i ; j <= n ; j += i){
if(dsu.find(i) == dsu.find(j)) continue ;
dsu.join(i, j) ;
grafo[i].push_back({j, m-i+1}) ; grafo[j].push_back({i, m-i+1}) ;
}
}
for(int i = 1 ; i < maxl ; i++){
for(int j = 1 ; j <= n ; j++) tab[i][j] = -1 ;
}
nivel[1] = 0 ;
dfs(1, 0) ;
for(int i = 1 ; i < maxl ; i++){
for(int j = 1 ; j <= n ; j++){
if(tab[i-1][j] == -1) continue ;
tab[i][j] = tab[i-1][tab[i-1][j]] ;
mx_t[i][j] = max(mx_t[i-1][j], mx_t[i-1][tab[i-1][j]]) ;
}
}
for(int i = 1 ; i <= q ; i++){
int a, b ; cin >> a >> b ;
cout << lca(a, b) << "\n" ;
}
}
Compilation message
pictionary.cpp: In member function 'int DSU::find(int)':
pictionary.cpp:13:65: warning: no return statement in function returning non-void [-Wreturn-type]
13 | int find(int a){(a == pai[a] ? a : pai[a] = find(pai[a])) ; }
| ^
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
37 ms |
65536 KB |
Execution killed with signal 9 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
41 ms |
65536 KB |
Execution killed with signal 9 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
41 ms |
65536 KB |
Execution killed with signal 9 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
37 ms |
65536 KB |
Execution killed with signal 9 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
39 ms |
65536 KB |
Execution killed with signal 9 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
37 ms |
65536 KB |
Execution killed with signal 9 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
42 ms |
65536 KB |
Execution killed with signal 9 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
43 ms |
65536 KB |
Execution killed with signal 9 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
39 ms |
65536 KB |
Execution killed with signal 9 |
2 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Runtime error |
37 ms |
65536 KB |
Execution killed with signal 9 |
2 |
Halted |
0 ms |
0 KB |
- |