제출 #342339

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
342339		cow	Hard route (IZhO17_road)	C++14	0 / 100	9 ms	12140 KiB

road

//
//  main.cpp
//  Hard Paths
//
//  Created by Isaac Noel on 1/1/21.
//

#include <iostream>
#include <vector>
#define ll long long
using namespace std;
#define mn (ll) 5e5+5

ll N;
vector<ll> graph[mn];
ll mD[mn][2];
ll mLoc, mDist, root;
ll dist[mn];
ll pa[mn];

ll ans, ansNum;
bool depthB;

ll dfs(ll l, ll p){
    pa[l] = p;
    for(ll j: graph[l]) if(j!=p) {
        dist[j] = dist[l]+1;
        if(dist[j] > mDist){
            mDist = dist[j];
            mLoc = j;
        }
        ll depC = dfs(j, l);
        if(!depthB) continue;
        if(depC >= mD[l][0]){
            mD[l][1] = mD[l][0];
            mD[l][0] = depC;
        } else mD[l][1] = max(mD[l][1], depC);
    }
    return depthB ? mD[l][0]+1 : 0;
}

ll dop=1, dPath;

void check(ll H){
    if(H > ans) {ans = H; ansNum = 0;}
    if(H == ans) {ansNum++;}
}
void retrace(ll loc){
    if(dop == dPath) return;
    if(graph[loc].size() < 3){
        if(ans == 0) ansNum = 1;
        dop++; retrace(pa[loc]);
        return;
    }
    ll dist = mD[loc][0];
    if(dist == dop) dist = mD[loc][1];
    ll H = dPath * dist; check(H);
    H = (dop+dist) * (dPath-dop); check(H);
    H = (dist + dPath-dop) * dop; check(H);
    dop++;
    retrace(pa[loc]);
}
int main() {
    cin >> N;
    for(ll i = 0; i < N-1; i++){
        ll a, b; cin >> a >> b;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    dfs(1,-1); root = mLoc; dist[root] = 0; mDist = 0;
    depthB = true;
    dPath = dfs(root, -1)-1;
    retrace(pa[mLoc]);
    cout << ans << " " << ansNum;
}

• Subtask 1: 0 / 19
• Subtask 2: 0 / 33
• Subtask 3: 0 / 48