Submission #1162171

#	Time	Username	Problem	Language	Result	Execution time	Memory
1162171		minhpk	Jakarta Skyscrapers (APIO15_skyscraper)	C++20	57 / 100	1100 ms	155376 KiB

skyscraper

#include <bits/stdc++.h>
using namespace std;


struct PairHash {
    size_t operator()(const pair<int, int>& p) const {
        auto h1 = std::hash<int>()(p.first);
        auto h2 = std::hash<int>()(p.second);
        return h1 ^ (h2 + 0x9e3779b97f4a7c15ULL + (h1 << 6) + (h1 >> 2));
    }
};

int a, b;
vector<int> z[1000005];
int blocksize;
pair<int, int> mark[30005];

struct node {
    int val, pos, type;
    bool operator>(const node &other) const {
        return val > other.val;
    }
};


unordered_map<pair<int, int>, int, PairHash> cnt;

void dijkstra() {
    priority_queue<node, vector<node>, greater<node>> q;
    q.push({0, mark[0].first, mark[0].second});
    cnt[{mark[0].first, mark[0].second}] = 0;

    while (!q.empty()) {
        node cur = q.top();
        q.pop();
        int val = cur.val, pos1 = cur.pos, type = cur.type;
        
        if (cnt[{pos1, type}] < val) continue;

        if (type == 0) {
            for (auto p : z[pos1]) {
                int newPos = pos1 + p;
                if (newPos < a) {
                    pair<int,int> key = {newPos, p};
                    if (!cnt.count(key) || cnt[key] > val + 1) {
                        cnt[key] = val + 1;
                        q.push({val + 1, newPos, p});
                    }
                }
                newPos = pos1 - p;
                if (newPos >= 0) {
                    pair<int,int> key = {newPos, p};
                    if (!cnt.count(key) || cnt[key] > val + 1) {
                        cnt[key] = val + 1;
                        q.push({val + 1, newPos, p});
                    }
                }
            }
        } else {
            
            pair<int,int> key0 = {pos1, 0};
            if (!cnt.count(key0) || cnt[key0] > val) {
                cnt[key0] = val;
                q.push({val, pos1, 0});
            }

            if (type > blocksize) {
                int step = 1;
                while (pos1 + step * type < a) {
                    int newPos = pos1 + step * type;
                    pair<int,int> key0 = {newPos, 0};
                    if (!cnt.count(key0) || cnt[key0] > val + step) {
                        cnt[key0] = val + step;
                        q.push({val + step, newPos, 0});
                    }
                    step++;
                }
                step = 1;
                while (pos1 - step * type >= 0) {
                    int newPos = pos1 - step * type;
                    pair<int,int> key0 = {newPos, 0};
                    if (!cnt.count(key0) || cnt[key0] > val + step) {
                        cnt[key0] = val + step;
                        q.push({val + step, newPos, 0});
                    }
                    step++;
                }
            } else {
                int newPos = pos1 + type;
                if (newPos < a) {
                    pair<int,int> key = {newPos, type};
                    if (!cnt.count(key) || cnt[key] > val + 1) {
                        cnt[key] = val + 1;
                        q.push({val + 1, newPos, type});
                    }
                }
                newPos = pos1 - type;
                if (newPos >= 0) {
                    pair<int,int> key = {newPos, type};
                    if (!cnt.count(key) || cnt[key] > val + 1) {
                        cnt[key] = val + 1;
                        q.push({val + 1, newPos, type});
                    }
                }
            }
        }
    }
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    cin >> a >> b;
    blocksize = sqrt(a);

    
    for (int i = 0; i < b; i++){
        int x, y;
        cin >> x >> y;
        z[x].push_back(y);
        mark[i] = {x, y};
    }
    if(b == 0){
        cout << -1;
        return 0;
    }

   
    

    dijkstra();

    pair<int,int> finalKey = {mark[1].first, 0};
    if(cnt.count(finalKey)){
        cout << cnt[finalKey];
    } else {
        cout << -1;
    }
    return 0;
}

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