Submission #219991

#	Time	Username	Problem	Language	Result	Execution time	Memory
219991		MKopchev	Jakarta Skyscrapers (APIO15_skyscraper)	C++14	100 / 100	110 ms	5624 KiB

skyscraper

#include<bits/stdc++.h>
using namespace std;
const int nmax=3e4+42;
int dist[nmax];
set<int> seen[nmax];

int m,n;

int wanted;
bool been[nmax];

priority_queue< pair<int/*dist*/,int/*node*/> > pq;

bool in(int where,int val)
{
    return seen[where].count(val);
}
int main()
{
    scanf("%i%i",&m,&n);

    for(int i=0;i<m;i++)dist[i]=1e9;

    int b,p;
    for(int i=0;i<n;i++)
    {
        scanf("%i%i",&b,&p);
        if(i==0){dist[b]=0;pq.push({0,b});}
        if(i==1)wanted=b;
        seen[b].insert(p);
    }

    while(pq.size())
    {
        pair<int/*dist*/,int/*node*/> current=pq.top();
        pq.pop();

        if(been[current.second])continue;
        been[current.second]=1;

        current.first=-current.first;

        if(current.second==wanted)
        {
            printf("%i\n",current.first);
            exit(0);
        }

        for(auto dog:seen[current.second])
        {
            for(int i=current.second+dog;i<m;i+=dog)
            {
                int dist_now=current.first+(i-current.second)/dog;
                if(dist[i]>dist_now)
                {
                    dist[i]=dist_now;
                    pq.push({-dist_now,i});
                }

                if(in(i,dog))break;
            }

            for(int i=current.second-dog;i>=0;i-=dog)
            {
                int dist_now=current.first+(current.second-i)/dog;
                if(dist[i]>dist_now)
                {
                    dist[i]=dist_now;
                    pq.push({-dist_now,i});
                }

                if(in(i,dog))break;
            }
        }
    }
    printf("-1\n");
    return 0;
}

Compilation message (stderr)

skyscraper.cpp: In function 'int main()':
skyscraper.cpp:20:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%i%i",&m,&n);
     ~~~~~^~~~~~~~~~~~~~
skyscraper.cpp:27:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%i%i",&b,&p);
         ~~~~~^~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 14 / 14
• Subtask 4: 21 / 21
• Subtask 5: 43 / 43