제출 #146994

#제출 시각아이디문제언어결과실행 시간메모리
146994gs14004City Mapping (NOI18_citymapping)C++17
70.01 / 100
35 ms8568 KiB
#include "citymapping.h"
#include <bits/stdc++.h>
#define sz(v) ((int)(v).size())
using namespace std;
using lint = long long;
using pi = pair<lint, lint>;
const int MAXN = 1005;

lint mem[MAXN][MAXN];

lint dist(int x, int y){
	if(x == y) return 0;
	if(mem[x][y]) return mem[x][y];
	return mem[x][y] = mem[y][x] = get_distance(x, y);
}

vector<pi> gph[MAXN];
lint dep[MAXN];
bool vis[MAXN];
vector<int> dfn;
int sz[MAXN], msz[MAXN];

void dfs(int x, int p){
	sz[x] = 1;
	msz[x] = 0;
	for(auto &i : gph[x]){
		if(!vis[i.second] && i.second != p){
			dfs(i.second, x);
			sz[x] += sz[i.second];
			msz[x] = max(msz[x], sz[i.second]);
		}
	}
	dfn.push_back(x);
}

int get_center(int v){
	dfn.clear();
	dfs(v, -1);
	pi ret(1e9, -1);
	for(auto &i : dfn){
		pi ans = pi(max(sz(dfn) - sz[i], msz[i]), i);
		ret = min(ret, ans);
	}
	return ret.second;
}

void find_roads(int N, int Q, int A[], int B[], int W[]) {
	auto make_edge = [&](int s, int e, int x){
//		printf("make_edge(%d, %d, %d)\n", s, e, x);
		gph[s].emplace_back(x, e);
		gph[e].emplace_back(x, s);
		for(int i=0; i<N-1; i++){
			if(!W[i]){
				tie(A[i], B[i], W[i]) = make_tuple(s, e, x);
				break;
			}
		}
	};
	int fp = 1;
	for(int i=1; i<=N; i++){
		if(dist(1, i) < dist(1, fp)) fp = i;
	}
	vector<pi> v;
	for(int i=1; i<=N; i++){
		if(i == fp) continue;
		dep[i] = dist(fp, i);
		v.emplace_back(dep[i], i);
	}
	sort(v.begin(), v.end());
	vector<int> prv = {fp};
	for(auto &i : v){
		if(sz(prv) == 1){
			make_edge(fp, i.second, i.first);
			prv.push_back(i.second);
			continue;
		}
		memset(vis, 0, sizeof(vis));
		int cur_check = 1;
		pi lowest(dep[fp], fp);
		while(!vis[cur_check]){
			int c = get_center(cur_check);
			vis[c] = 1;
			if(dep[c] + dist(c, i.second) == i.first){
				lowest = max(lowest, pi(dep[c], c));
				vector<int> sons;
				for(auto &j : gph[c]){
					if(dep[j.second] > dep[c]){
						sons.push_back(j.second);
					}
				}
				if(sons.empty()) break;
				cur_check = sons.back();
				for(int j=0; j<sz(sons)-1; j++){
					if(dep[sons[j]] + dist(sons[j], i.second) == i.first){
						cur_check = sons[j];
					}
				}
			}
			else{
				for(auto &j : gph[c]){
					if(dep[j.second] < dep[c]){
						cur_check = j.second;
						break;
					}
				}
			}
		}
		make_edge(lowest.second, i.second, dist(lowest.second, i.second));
		prv.push_back(i.second);
	}
}
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