Submission #580860

#	Time	Username	Problem	Language	Result	Execution time	Memory
580860		benson1029	Race (IOI11_race)	C++14	0 / 100	2 ms	4948 KiB

race

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

vector< pair<int,int> > edg[200005];
int k;
bool solved[200005];
int mxdeg, centroid;
vector< pair<long long, int> > v, v2;
int ans = 1e9;

void findcentroid(int x, int p) {
	int deg = 0;
	if(p!=-1) ++deg;
	for(auto i:edg[x]) {
		if(!solved[i.first] && i.first!=p) {
			findcentroid(i.first, x);
			++deg;
		}
	}
	if(deg > mxdeg) {
		mxdeg = deg;
		centroid = x;
	}
}

void solve(int x);

void findandsolve(int x) {
	mxdeg = -1;
	findcentroid(x, -1);
	solve(centroid);
}

void dfs(int x, int p, long long len, int cnt) {
	v.push_back({len, cnt});
	for(auto i:edg[x]) {
		if(solved[i.first]) continue;
		if(i.first != p) {
			dfs(i.first, x, len+i.second, cnt+1);
		}
	}
}

void solve(int x) {
	v.clear(); v2.clear();
	v2.push_back({0, 0});
	solved[x] = true;
	for(auto i:edg[x]) {
		if(solved[i.first]) continue;
		v.clear();
		dfs(i.first, -1, i.second, 1);
		sort(v.begin(), v.end());
		for(auto i:v) {
			int tmp = lower_bound(v2.begin(), v2.end(), make_pair(k-i.first, 0)) - v2.begin();
			if(tmp < v2.size() && v2[tmp].first == k-i.first) {
				ans = min(ans, v2[tmp].second + i.second);
			}
		}
		for(auto i:v) {
			v2.push_back(i);
		}
	}
}

int best_path(int N, int K, int H[][2], int L[])
{
	k = K;
	for(int i=0; i<N-1; i++) {
		edg[H[i][0]].push_back({H[i][1], L[i]});
		edg[H[i][1]].push_back({H[i][0], L[i]});
	}
	findandsolve(0);
	if(ans==1e9) return -1;
	return ans;
}

Compilation message (stderr)

race.cpp: In function 'void solve(int)':
race.cpp:56:11: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<long long int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   56 |    if(tmp < v2.size() && v2[tmp].first == k-i.first) {
      |       ~~~~^~~~~~~~~~~

• Subtask 1: 0 / 9
• Subtask 2: 0 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57