Submission #422780

#	Time	Username	Problem	Language	Result	Execution time	Memory
422780		alireza_kaviani	Highway Tolls (IOI18_highway)	C++11	5 / 100	279 ms	15452 KiB

highway

#include "highway.h"
#include <bits/stdc++.h>
using namespace std;

typedef pair<int, int> pii;

const int MAXN = 2e5 + 10;
int n , timer , st[MAXN] , prv[MAXN];
vector<pii> adj[MAXN];

vector<int> get(int x){
	vector<int> ans(n - 1 , 0);
	for(int i = 0 ; i < n ; i++){
		if(st[i] >= x)	ans[prv[i]] = 1;
	}
	return ans;
}

void DFS(int v , int p = -1){
	st[v] = ++timer;
	for(pii i : adj[v]){
		int u = i.first , w = i.second;
		if(u == p)	continue;
		prv[u] = w;
		DFS(u , v);
	}
}

int solve(int root){
	fill(st , st + MAXN , 0);
	fill(prv , prv + MAXN , -1);
	timer = 0 , DFS(root);
	int l = 0 , r = n , dist = ask(get(n));
	while(r - l > 1){
		int mid = l + r >> 1;
		if(ask(get(mid)) > dist)	l = mid;
		else	r = mid;
	}
	for(int i = 0 ; i < n ; i++)	if(st[i] == l)	return i;
}

void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
	if(U.size() != N - 1)	return; n = N;
	for(int i = 0 ; i < n - 1 ; i++){
		adj[V[i]].push_back({U[i] , i});
		adj[U[i]].push_back({V[i] , i});
	}
	int s = solve(0) , t = solve(s);
	answer(s , t);
}

Compilation message (stderr)

highway.cpp: In function 'int solve(int)':
highway.cpp:35:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   35 |   int mid = l + r >> 1;
      |             ~~^~~
highway.cpp: In function 'void find_pair(int, std::vector<int>, std::vector<int>, int, int)':
highway.cpp:43:14: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   43 |  if(U.size() != N - 1) return; n = N;
      |     ~~~~~~~~~^~~~~~~~
highway.cpp:43:2: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   43 |  if(U.size() != N - 1) return; n = N;
      |  ^~
highway.cpp:43:32: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   43 |  if(U.size() != N - 1) return; n = N;
      |                                ^
highway.cpp: In function 'int solve(int)':
highway.cpp:40:1: warning: control reaches end of non-void function [-Wreturn-type]
   40 | }
      | ^

• Subtask 1: 5 / 5
• Subtask 2: 0 / 7
• Subtask 3: 0 / 6
• Subtask 4: 0 / 33
• Subtask 5: 0 / 18
• Subtask 6: 0 / 31