Submission #679532

#	Time	Username	Problem	Language	Result	Execution time	Memory
679532		Dan4Life	Swapping Cities (APIO20_swap)	C++17	0 / 100	26 ms	51172 KiB

swap

#include "swap.h"
#include <bits/stdc++.h>
using namespace std;
#define pb push_back

const int maxn = (int)5e5+10;
const int lgn = 20;

int n, m, num;
int jmp[lgn][maxn];
vector<int> adj[maxn];
bool line[maxn], good[maxn];
struct Edge{ int u, v, w; };
int p[maxn], lev[maxn], wei[maxn], deg[maxn];

Edge edge[maxn];

int getPath(int x, int steps){
	for(int i = lgn-1; i >= 0; i--)
		if(steps&(1<<i) and x!=-1) x = jmp[i][x];
	return x; 
}

int lca(int a, int b){
	if(a==b) return a;
	if(jmp[0][a]==jmp[0][b]) return jmp[0][a];
	if(lev[a] < lev[b]) swap(a,b);
	a = getPath(a, lev[a]-lev[b]);
	for(int i = lgn-1; i >= 0; i--)
		if(jmp[i][a]!=-1 and jmp[i][a]!=jmp[i][b])
			a = jmp[i][a], b = jmp[i][b];
	return lca(a,b);
}

int findSet(int i){ return p[i]==i?i:p[i]=findSet(p[i]); }
bool isSameSet(int i, int j) { return findSet(i)==findSet(j); }

void unionSet(Edge &e){
	int i = e.u, j = e.v; wei[num] = e.w;
	int x = findSet(i), y = findSet(j);
	deg[x]++, deg[y]++;
	p[x]=p[y]=p[num]=num;
	if(x!=y) adj[num].pb(y);
	adj[num].pb(x); line[num]^=(x==y) | !line[x] | !line[y];
	good[num] |= good[x] | good[y] | !line[num] | (deg[x]>=3) | (deg[y]>=3);
	deg[num] = 2-(x==y); num++;
}

void dfs(int s, int p){
	if(p!=-1) lev[s] = lev[p]+1, jmp[0][s] = p;
	for(auto u : adj[s]) if(u!=p) dfs(u,s);
}

void init(int N, int M, vector<int> u, vector<int> v, vector<int> w) {
	n = N, m = M; num = n; memset(jmp,-1,sizeof(jmp));
	for(int i = 0; i <= n+m; i++) p[i] = i, line[i] = 1;
	for(int i = 0; i < m; i++) edge[i] = {u[i],v[i],w[i]};
	sort(edge,edge+m,[&](Edge &x, Edge &y){ return x.w<y.w; });
	for(int i = 0; i < m; i++) unionSet(edge[i]);
	dfs(num-1,-1);
	for(int i = 1; i < lgn; i++)
		for(int j = 0; j+(1<<i)-1 < num; j++)
			if(jmp[i-1][j]!=-1) jmp[i][j] = jmp[i-1][jmp[i-1][j]];
}

int getMinimumFuelCapacity(int x, int y) {
	int z = lca(x,y);
	while(jmp[0][z]!=-1 and !good[z])
		for(int i = lgn-1; i >= 0; i--) 
			if(jmp[i][z]!=-1 and !good[z]) z = jmp[i][z];
	if(good[z]) return wei[z];
	if(jmp[0][z]!=-1) z=jmp[0][z];
	return good[z]?wei[z]:-1;
}

/*
5 6
0 1 4
0 2 4
1 2 1
1 3 2
1 4 10
2 3 3
3
1 2
2 4
0 1
*/

• Subtask 1: 0 / 6
• Subtask 2: 0 / 7
• Subtask 3: 0 / 17
• Subtask 4: 0 / 20
• Subtask 5: 0 / 23
• Subtask 6: 0 / 27