Submission #738865

#	Time	Username	Problem	Language	Result	Execution time	Memory
738865		josanneo22	Swapping Cities (APIO20_swap)	C++17	50 / 100	2061 ms	18188 KiB

swap

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

#define pb push_back
#define mp make_pair
#define fi first
#define se second

vector<int> par,sz,swappable,deg,has;
int total_groups;
void init(int n){
	par.resize(n); sz.resize(n); swappable.resize(n); deg.resize(n);has.resize(n);
	for(int i=0;i<n;i++){
		par[i]=i;
		sz[i]=1;
        swappable[i]=0;
        deg[i]=0;
        has[i]=0;
	}
}
int find(int x){
	if(par[x]==x) return x;
	else return par[x]=find(par[x]);
}
void sw(int x,int y){ 
    swappable[x]=(swappable[x]&swappable[y]);
    swappable[y]=(swappable[x]&swappable[y]);
    has[x]|=has[y];
    if(has[x]){
        swappable[y]=1;
        swappable[x]=1;
    }
}
void unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y) return;
    if (sz[x] < sz[y]) swap(x, y);
    sw(x,y);
    par[y] = x;
    sz[x] += sz[y];
    total_groups--;
}
bool same(int x,int y){
    x = find(x);
    y = find(y);
    if(x==y) return true;
    else return false;
}
//remember to init(n+5) and total_groups=n

struct edge{
    int u,v,d;
};
bool operator <(edge a,edge b){
    return a.d<b.d;
}

#include "swap.h"
int n,m,ok=1,mx=-1;
int sub1=1,sub2=1,sub4=1,sub5=1;
vector<int> tw;
vector<vector<pair<int,int>>> adj;
vector<edge> ed;
void init(int N, int M, vector<int> U, vector<int> V, vector<int> W) {
    n=N,m=M;tw.resize(n+2);
    adj.resize(n + 2);
    for (int i = 0; i < m; i++) {
        adj[U[i]].push_back(make_pair(V[i],W[i]));
        adj[V[i]].push_back(make_pair(U[i], W[i]));
        mx = max(mx, W[i]);
    }
    for (int i = 0; i < n; i++) {
        sub1&=(adj[i].size() <= 2);
        ok&=(adj[i].size()==2);
    }
    for(int i=0;i<m;i++){
        if(U[i]!=0) sub2=0;
        tw[V[i]]=W[i];
    }
    for(int i=0;i<m;i++){
        ed.pb({U[i],V[i],W[i]});
    }
    sort(ed.begin(),ed.end());
}

int getMinimumFuelCapacity(int X, int Y) {
    if(sub1){
        if(ok) return mx;
        else return -1;
    }
    if(sub2){
        if(m<=2) return -1;
        if(X>Y) swap(X,Y);
        if(X!=0){//if both at side
            int ret=max(tw[Y],tw[X]);
            int cnt=0;
            while(ed[cnt].v==X || ed[cnt].v==Y) cnt++;
            ret=max(ret,ed[cnt].d);
            return ret;
        }
        else{
            int ret=tw[Y],tmp,cnt=0;
            while(ed[cnt].v==Y) cnt++; 
            ret=max(ret,ed[cnt].d);
            tmp=ed[cnt].v;
            cnt++;
            while(ed[cnt].v==Y || ed[cnt].v==tmp) cnt++; 
            ret=max(ret,ed[cnt].d);
            return ret;
        }
    }
    init(n+2); 
    int i=0;
    while(i<=m-1 && (!same(X,Y) || !swappable[find(X)])){
        deg[ed[i].u]++; deg[ed[i].v]++;
        if(same(ed[i].u,ed[i].v)) has[find(ed[i].u)]=1;
        if(deg[ed[i].u]>=3) has[find(ed[i].u)]=1;
        if(deg[ed[i].v]>=3) has[find(ed[i].v)]=1;
        unite(ed[i].u,ed[i].v);
        if(same(X,Y) && has[find(X)]==1) return ed[i].d;
        i++;
    }
    return -1; 
}
/*int main(){
    int tt; cin>>tt;
    while(tt--){
        int n,m; cin>>n>>m;
        vector<int>u(m),v(m),w(m);
        for(int i=0;i<m;i++) cin>>u[i]>>v[i]>>w[i];
        init(n,m,u,v,w);
        int q; cin>>q;
        for(int i=0;i<q;i++){
            int x,y; cin>>x>>y;
            cout<<getMinimumFuelCapacity(x,y)<<'\n';
        }
    }
}*/

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