Submission #555450

#	Time	Username	Problem	Language	Result	Execution time	Memory
555450		SmolBrain	Jakarta Skyscrapers (APIO15_skyscraper)	C++17	100 / 100	986 ms	198364 KiB

skyscraper

// Om Namah Shivaya
// GM in 94 days

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define endl '\n'
#define pb push_back
#define conts continue
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "YES" << endl
#define no cout << "NO" << endl
#define ff first
#define ss second
#define ceil2(x,y) ((x+y-1) / (y))
#define sz(a) a.size()
#define setbits(x) __builtin_popcountll(x)
#ifndef ONLINE_JUDGE
#define debug(x) cout << #x <<" = "; print(x); cout << endl
#else
#define debug(x)
#endif

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

bool iseven(ll n) {if ((n & 1) == 0) return true; return false;}

void print(ll t) {cout << t;}
void print(int t) {cout << t;}
void print(string t) {cout << t;}
void print(char t) {cout << t;}
void print(double t) {cout << t;}
void print(ld t) {cout << t;}

template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T, class V> void print(pair <T, V> p) {cout << "{"; print(p.ff); cout << ","; print(p.ss); cout << "}";}
template <class T> void print(vector <T> v) {cout << "[ "; for (T i : v) {print(i); cout << " ";} cout << "]";}
template <class T> void print(set <T> v) {cout << "[ "; for (T i : v) {print(i); cout << " ";} cout << "]";}
template <class T> void print(multiset <T> v) {cout << "[ "; for (T i : v) {print(i); cout << " ";} cout << "]";}
template <class T, class V> void print(map <T, V> v) {cout << "[ "; for (auto i : v) {print(i); cout << " ";} cout << "]";}
template<typename T> void amin(T &a, T b) { a = min(a, b); }
template<typename T> void amax(T &a, T b) { a = max(a, b); }

void usaco(string filename) {
    freopen((filename + ".in").c_str(), "r", stdin);
    freopen((filename + ".out").c_str(), "w", stdout);
}

const int MOD = 1e9 + 7;
const int maxn = 3e4 + 5;
const int inf1 = 1e9 + 5;
const ll inf2 = ll(1e18) + 5;
const int block_size = 175;

vector<array<int, 3>> adj[maxn][block_size];
bool vis[maxn][block_size];
int dis[maxn][block_size];

void solve(int test_case)
{
    // editorial approach
    int n, m; cin >> n >> m;
    vector<pii> a(m);

    rep(i, m) {
        int b, p; cin >> b >> p;
        a[i] = {b, p};

        if (p < block_size) {
            adj[b][0].pb({b, p, 0});
        }
        else {
            int w = 0;

            for (int j = b - p; j >= 0; j -= p) {
                w++;
                adj[b][0].pb({j, 0, w});
            }

            w = 0;

            for (int j = b + p; j < n; j += p) {
                w++;
                adj[b][0].pb({j, 0, w});
            }
        }
    }

    priority_queue< array<int, 3>, vector<array<int, 3>>, greater<array<int, 3>> > pq;
    rep(i, n) rep(j, block_size) dis[i][j] = inf1;

    if (a[0].ss < block_size) {
        pq.push({0, a[0].ff, a[0].ss});
        dis[a[0].ff][a[0].ss] = 0;
    }
    else {
        pq.push({0, a[0].ff, 0});
        dis[a[0].ff][0] = 0;
    }

    auto add = [&](int cost, int b, int p) {
        if (cost < dis[b][p]) {
            dis[b][p] = cost;
            pq.push({cost, b, p});
        }
    };

    while (!pq.empty()) {
        auto [cost, b, p] = pq.top();
        pq.pop();

        if (vis[b][p]) conts;
        vis[b][p] = 1;

        if (b == a[1].ff) {
            cout << cost << endl;
            return;
        }

        // add edge to dummy vertex of b
        add(cost, b, 0);

        // go 1 step left / 1 step right
        if (p > 0) {
            if (b - p >= 0) add(cost + 1, b - p, p);
            if (b + p < n) add(cost + 1, b + p, p);
        }

        // traverse other edges and add them
        for (auto [b2, p2, w] : adj[b][p]) {
            add(cost + w, b2, p2);
        }
    }

    cout << -1 << endl;
}

int main()
{
    chrono::steady_clock::time_point begin = chrono::steady_clock::now();

    fastio;

    int t = 1;
    // cin >> t;
    rep1(i, t) {
        solve(i);
    }

    chrono::steady_clock::time_point end = chrono::steady_clock::now();
    cerr << "[Finished in " << chrono::duration_cast<chrono::microseconds>(end - begin).count() / 1000 << "ms]" << endl;

    return 0;
}

Compilation message (stderr)

skyscraper.cpp: In function 'void usaco(std::string)':
skyscraper.cpp:64:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   64 |     freopen((filename + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
skyscraper.cpp:65:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   65 |     freopen((filename + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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