Submission #297535

#TimeUsernameProblemLanguageResultExecution timeMemory
297535AaronNaiduJakarta Skyscrapers (APIO15_skyscraper)C++14
0 / 100
3 ms2748 KiB
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int n, m, b, p;
vector<int> doges[50000];
vector<pair<int, int> > graph[50000];
int powers[50000];
int positions[50000];
priority_queue<pair<int, int> > q;
int dists[50000];
bool visited[50000];
bool visited2[50000]; //position
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    cin >> n >> m;
    for (int i = 0; i < m; i++)
    {
        cin >> b >> p;
        powers[i] = p;
        positions[i] = b;
        doges[b].push_back(i);
        dists[i] = 1000000000;
    }
    q.push({0, 0});
    dists[0] = 0;
    while (!q.empty()) 
    {
        int x = q.top().second;
       //cout << "At node " << x << " which is " << dists[x] << " away\n";
        if (x == 1)
        {
            int ans = dists[1];
            cout << ans << "\n";
            return 0;
        }
        q.pop();
        if (visited[x])
        {
            continue;
        }
        visited[x] = true;
        int jumpCount = -1;
        for (int j = positions[x]; j < n; j+=powers[x])
        {
            if (visited2[j])
            {
                continue;
            }
            visited2[j] = true;
            jumpCount++;
            for (auto k : doges[j])
            {
                if (!visited[k] and dists[x] + jumpCount < dists[k])
                {
                    if (k == 1 or powers[k] != powers[x])
                    {
                        dists[k] = dists[x] + jumpCount;
                        q.push({-dists[k], k});
                    }
                }     
            }
        }
        jumpCount = 0;
        for (int j = positions[x]-powers[x]; j >= 0; j-=powers[x])
        {
            if (visited2[j])
            {
                continue;
            }
            visited2[j] = true;
            jumpCount++;
            for (auto k : doges[j])
            {
                if (!visited[k] and dists[x] + jumpCount < dists[k])
                {
                    if (k == 1 or powers[k] != powers[x])
                    {
                        dists[k] = dists[x] + jumpCount;
                        q.push({-dists[k], k});
                    }
                }
            }
        }
    }
    cout << "-1\n";
}
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