제출 #1054750

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1054750		alexander707070	자매 도시 (APIO20_swap)	C++14	0 / 100	78 ms	45416 KiB

swap

#include<bits/stdc++.h>
#include "swap.h"

#define MAXN 100007
using namespace std;

const int inf=1e9+7;

int n,m,a[MAXN],b[MAXN],c[MAXN],dep[MAXN];
vector< pair<int,int> > tree[MAXN];
vector<int> v[MAXN];
int parent[MAXN],res[MAXN],es[MAXN];

struct info{
    int par,mins,maxe;
};

struct edge{
    int from,to,cost;

    inline friend bool operator < (edge fr,edge sc){
        return fr.cost<sc.cost;
    }
}e[MAXN];

struct unionfind{
    int dsu[MAXN],sz[MAXN];

    void init(){
        for(int i=1;i<=n;i++){
            dsu[i]=i; sz[i]=1;
        }
    }

    int root(int x){
        if(dsu[x]==x)return dsu[x];
        return root(dsu[x]);
    }

    void mergev(int x,int y){
        int rootx=root(x);
        int rooty=root(y);

        if(rootx==rooty)return;
        if(sz[rootx]<sz[rooty])swap(rootx,rooty);

        dsu[rooty]=rootx;
        sz[rootx]+=sz[rooty];
    }

    bool connected(int x,int y){
        return root(x)==root(y);
    }
}graph;

info dp[MAXN][20];

void dfs(int x,int p,int ee){
    parent[x]=p;
    dep[x]=dep[p]+1;
    es[x]=ee;

    dp[x][0].par=parent[x];
    dp[x][0].mins=min(res[x],res[parent[x]]);
    dp[x][0].maxe=ee;

    for(int t=1;t<20;t++){
        dp[x][t].par=dp[dp[x][t-1].par][t-1].par;
        dp[x][t].mins=min( dp[x][t-1].mins , dp[dp[x][t-1].par][t-1].mins );
        dp[x][t].maxe=max( dp[x][t-1].maxe , dp[dp[x][t-1].par][t-1].maxe );
    }

    for(pair<int,int> i:tree[x]){
        if(i.first==p)continue;
        dfs(i.first,x,i.second);
    }
}

int getbranch(int x,int y){
    int ans=inf;

    if(dep[x]<dep[y])swap(x,y);

    if(x==y or parent[x]==y)return inf;

    if(dep[x]!=dep[y]){
        x=parent[x];

        for(int i=19;i>=0;i--){
            if(dep[x]-dep[y]>(1<<i)){
                ans=min(ans,dp[x][i].mins);
                x=dp[x][i].par;
            }
        }
        
        if(parent[x]==y)return ans;

        if(dep[x]>dep[y]){
            x=parent[x];
            ans=min(ans,res[x]);
        }
    }

    x=parent[x];
    y=parent[y];

    ans=min(ans,res[x]);

    for(int i=19;i>=0;i--){
        if(dp[x][i].par!=0 and dp[y][i].par!=0 and dp[x][i].par!=dp[y][i].par){
            ans=min(ans,dp[x][i].mins);
            ans=min(ans,dp[y][i].mins);

            x=dp[x][i].par; y=dp[y][i].par;
        }
    }

    if(x!=y)ans=min(ans,res[parent[x]]);

    return ans;
}

int getedge(int x,int y){
    if(dep[x]>dep[y])swap(x,y);

    int ans=0;
    for(int i=19;i>=0;i--){
        if(dep[x]-dep[y]>(1<<i)){
            ans=max(ans,dp[x][i].maxe);
            x=dp[x][i].par;
        }
    }

    if(parent[x]==y)return ans;
    
    ans=max(ans,dp[x][0].maxe);
    x=dp[x][0].par;

    for(int i=19;i>=0;i--){
        if(dp[x][i].par!=0 and dp[y][i].par!=0 and dp[x][i].par!=dp[y][i].par){
            ans=max(ans,dp[x][i].maxe);
            ans=max(ans,dp[y][i].maxe);

            x=dp[x][i].par; y=dp[y][i].par;
        }
    }

    return ans;
}

void init(int N, int M,vector<int> U, vector<int> V, vector<int> W) {
    n=N; m=M;
    for(int i=1;i<=m;i++){
        a[i]=U[i-1]+1; b[i]=V[i-1]+1; c[i]=W[i-1];

        v[a[i]].push_back(c[i]);
        v[b[i]].push_back(c[i]);

        e[i]={a[i],b[i],c[i]};
    }

    for(int i=1;i<=n;i++){
        sort(v[i].begin(),v[i].end());

        res[i]=inf;
        if(v[i].size()>=3)res[i]=v[i][2];
    }
    res[0]=inf;

    sort(e+1,e+m+1);
    graph.init();

    for(int i=1;i<=m;i++){
        if(graph.connected(e[i].from,e[i].to))continue;
        
        tree[e[i].from].push_back({e[i].to,e[i].cost});
        tree[e[i].to].push_back({e[i].from,e[i].cost});

        graph.mergev(e[i].from,e[i].to);
    }

    for(int t=0;t<20;t++)dp[0][t]={0,inf,0};
    dfs(1,0,0);
}

int getMinimumFuelCapacity(int X, int Y) {
    if(X==0 or Y==0 or n<=3)return -1;
    if(res[1]==inf)cout<<1/0;
    return max(res[1],max(es[X+1],es[Y+1]));

    int ans=getbranch(X+1,Y+1);

    if(ans==inf)return -1;
    return max(ans,getedge(X+1,Y+1));
}

/*
int main(){
    init(5, 6, {0, 0, 1, 1, 1, 2}, {1, 2, 2, 3, 4, 3}, {4, 4, 1, 2, 10, 3});

    cout<<getMinimumFuelCapacity(1, 2)<<"\n";
    cout<<getMinimumFuelCapacity(2,4)<<"\n";
    cout<<getMinimumFuelCapacity(0,1)<<"\n";
}
*/

컴파일 시 표준 에러 (stderr) 메시지

swap.cpp: In function 'int getMinimumFuelCapacity(int, int)':
swap.cpp:188:27: warning: division by zero [-Wdiv-by-zero]
  188 |     if(res[1]==inf)cout<<1/0;
      |                          ~^~

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