Submission #678715

#	Time	Username	Problem	Language	Result	Execution time	Memory
678715		qwerasdfzxcl	Jakarta Skyscrapers (APIO15_skyscraper)	C++17	57 / 100	1099 ms	87484 KiB

skyscraper

#include <bits/stdc++.h>

typedef long long ll;
using namespace std;
constexpr int INF = 1e9+100;

struct my_bitset{
    unsigned long long bit[500];
    bool find(int x){return bit[x/64]&(1LL<<(x&63));}
    void insert(int x){bit[x/64] |= (1LL<<(x&63));}
};

int dist[30030], visited[30030];
set<int> st[30030];
vector<int> a[30030];

struct Vertex{
    int s, p;
    Vertex(){}
    Vertex(int _s, int _p): s(_s), p(_p) {}
    //bool operator < (const Vertex &V) const{return d > V.d;}
};

int main(){
    int n, m, s, e;
    scanf("%d %d", &n, &m);
    for (int i=1;i<=m;i++){
        int x, p;
        scanf("%d %d", &x, &p);
        ++x;

        a[x].push_back(p);

        if (i==1) s = x;
        if (i==2) e = x;
    }

    fill(dist+1, dist+n+1, INF);
    fill(visited+1, visited+n+1, 0);
    dist[s] = 0;
    for (int i=1;i<=n;i++){
        sort(a[i].begin(), a[i].end());
        a[i].erase(unique(a[i].begin(), a[i].end()), a[i].end());
    }

    stack<Vertex, vector<Vertex>> pq[2];
    pq[0].emplace(s, 0);
    int d = 0;

    while(true){
        if (pq[d&1].empty() && pq[(d+1)&1].empty()) break;
        if (pq[d&1].empty()) {d++; continue;}

        auto [s, p] = pq[d&1].top(); pq[d&1].pop();
        dist[s] = min(dist[s], d);
        if (p){
            if (st[s].find(p)!=st[s].end()) continue;
            st[s].insert(p);
            if (s-p > 0) pq[(d+1)&1].emplace(s-p, p);
            if (s+p <= n) pq[(d+1)&1].emplace(s+p, p);
        }

        if (!visited[s]){
            visited[s] = 1;
            for (auto &p2:a[s]){
                st[s].insert(p2);
                if (s-p2 > 0) pq[(d+1)&1].emplace(s-p2, p2);
                if (s+p2 <= n) pq[(d+1)&1].emplace(s+p2, p2);
            }
        }
    }

    if (dist[e]==INF) printf("-1\n");
    else printf("%d\n", dist[e]);
    return 0;
}

Compilation message (stderr)

skyscraper.cpp: In function 'int main()':
skyscraper.cpp:26:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   26 |     scanf("%d %d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~~
skyscraper.cpp:29:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   29 |         scanf("%d %d", &x, &p);
      |         ~~~~~^~~~~~~~~~~~~~~~~
skyscraper.cpp:20:40: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
   20 |     Vertex(int _s, int _p): s(_s), p(_p) {}
      |                                        ^
skyscraper.cpp:25:15: note: 's' was declared here
   25 |     int n, m, s, e;
      |               ^
skyscraper.cpp:73:15: warning: 'e' may be used uninitialized in this function [-Wmaybe-uninitialized]
   73 |     if (dist[e]==INF) printf("-1\n");
      |         ~~~~~~^

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 14 / 14
• Subtask 4: 21 / 21
• Subtask 5: 0 / 43