Submission #171078

#	Time	Username	Problem	Language	Result	Execution time	Memory
171078		juggernaut	Evacuation plan (IZhO18_plan)	C++14	100 / 100	900 ms	102084 KiB

plan

//Just try and the idea will come!
#include<bits/stdc++.h>
#define int long long int
using namespace std;
vector<vector<pair<int,int>>>g(100001);
vector<pair<int,int>>p;
int n,m,x,y,z,i,dis[100001],par[100001],sz[100001],up[100001][20],sp[100001][20],timer,tin[100001],tout[100001];
int fn(int v){
    if(v==par[v])return v;
    return par[v]=fn(par[v]);
}
void dfs(int v,int p,int cost){
    tin[v]=timer++;
    up[v][0]=p;
    sp[v][0]=cost;
    for(int i=1;i<20;i++){
        up[v][i]=up[up[v][i-1]][i-1];
        sp[v][i]=min(sp[v][i-1],sp[up[v][i-1]][i-1]);
    }
    for(pair<int,int>to:g[v]){
        if(to.first!=p)dfs(to.first,v,to.second);
    }
    tout[v]=timer++;
}
bool upper(int a,int b){
    return tin[a]<tin[b]&&tout[a]>tout[b]||a==0||b==0;
}
int lca(int a,int b){
	if(upper(a,b))return a;
	if(upper(b,a))return b;
	for(int i=19;i>=0;i--)if(!upper(up[a][i],b))a=up[a][i];
	return up[a][0];
}
int fin(int a,int p){
    int res=1e15;
    for(int i=19;i>=0;i--)
        if(!upper(up[a][i],p)){
            res=min(res,sp[a][i]);
            a=up[a][i];
        }
    return res;
}
main(){
    scanf("%lld%lld",&n,&m);
    while(m--){
        scanf("%lld%lld%lld",&x,&y,&z);
        g[x].push_back({y,z});
        g[y].push_back({x,z});
        p.push_back({x,y});
    }
    for(i=1;i<=n;i++)dis[i]=1e15;
    scanf("%lld",&m);
    priority_queue<pair<int,int>>q;
    while(m--){
        scanf("%lld",&x);
        dis[x]=0;
        q.push({0,x});
    }
    while(!q.empty()){
        x=q.top().second;
        y=-q.top().first;
        q.pop();
        if(y>dis[x])continue;
        for(auto to:g[x]){
            if(dis[to.first]>y+to.second){
                dis[to.first]=y+to.second;
                q.push({-y-to.second,to.first});
            }
        }
    }
    vector<pair<int,pair<int,int>>>vec;
    for(auto to:p)vec.push_back({min(dis[to.first],dis[to.second]),to});
    sort(vec.rbegin(),vec.rend());
    for(i=1;i<=n;i++)g[i].clear(),par[i]=i,sz[i]=1;
    for(auto to:vec){
        x=fn(to.second.first);
        y=fn(to.second.second);
        if(x!=y){
            if(sz[x]<sz[y])swap(x,y);
            par[y]=x;
            sz[x]+=sz[y];
            g[to.second.first].push_back({to.second.second,to.first});
            g[to.second.second].push_back({to.second.first,to.first});
        }
    }
    scanf("%lld",&m);
    dfs(1,0,1e15);
    while(m--){
        scanf("%lld%lld",&x,&y);
        int l=lca(x,y);
        printf("%lld\n",min(fin(x,l),fin(y,l)));
    }
}

Compilation message (stderr)

plan.cpp: In function 'bool upper(long long int, long long int)':
plan.cpp:26:25: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
     return tin[a]<tin[b]&&tout[a]>tout[b]||a==0||b==0;
            ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~
plan.cpp: At global scope:
plan.cpp:43:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main(){
      ^
plan.cpp: In function 'int main()':
plan.cpp:44:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld%lld",&n,&m);
     ~~~~~^~~~~~~~~~~~~~~~~~
plan.cpp:46:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld%lld%lld",&x,&y,&z);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
plan.cpp:52:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld",&m);
     ~~~~~^~~~~~~~~~~
plan.cpp:55:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld",&x);
         ~~~~~^~~~~~~~~~~
plan.cpp:86:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld",&m);
     ~~~~~^~~~~~~~~~~
plan.cpp:89:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld%lld",&x,&y);
         ~~~~~^~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 13 / 13
• Subtask 3: 12 / 12
• Subtask 4: 19 / 19
• Subtask 5: 46 / 46