Submission #248518

#	Time	Username	Problem	Language	Result	Execution time	Memory
248518		sahil_k	Jakarta Skyscrapers (APIO15_skyscraper)	C++14	100 / 100	195 ms	65764 KiB

skyscraper

#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <cmath>
#include <queue>
using namespace std;
/*
int n, m;
set<int> inc[30100];
vector< pair<int, int> > adj[2000000];
int dist[2000000];
bool vis[2000000];
priority_queue< pair<int, int> > ord;
int main () {
	cin >> n >> m;
	int rt = sqrt(n);
	int start, end;
	for (int i=0; i<n; i++) {
		for (int j=1; j<rt; j++) {
			adj[i*rt+j].push_back({i*rt, 0});
			if (i-j >= 0) adj[i*rt+j].push_back({(i-j)*rt+j, 1});
			if (i+j < n) adj[i*rt+j].push_back({(i+j)*rt+j, 1});
		}
	}
	int bi, pi;
	for (int i=0; i<m; i++) {
		cin >> bi >> pi;
		if (i == 0) start = bi;
		if (i == 1) end = bi;
		if (pi < rt) {
			adj[bi*rt].push_back({bi*rt+pi, 0});
		} else {
			for (int j=1; j<n; j++) {
				if (bi-j*pi < 0 && bi+j*pi >= n) break;
				if (bi-j*pi >= 0) adj[bi*rt].push_back({(bi-j*pi)*rt, j});
				if (bi+j*pi < n) adj[bi*rt].push_back({(bi+j*pi)*rt, j});
			}
		}
	}
	for (int i=0; i<n*rt; i++) {
		dist[i] = 1e9;
		vis[i] = false;
	}
	dist[start*rt] = 0;
	ord.push({0, start*rt});
	while (ord.size() > 0) {
		pair<int, int> cur = ord.top();
		cur.first = -cur.first;
		ord.pop();
		if (cur.second == end*rt) {
			cout << cur.first << endl;
			return 0;
		}
		if (vis[cur.second]) continue;
		vis[cur.second] = true;
		for (auto i: adj[cur.second]) {
			if (!vis[i.first] && cur.first+i.second < dist[i.first]) {
				dist[i.first] = cur.first+i.second;
				ord.push({-dist[i.first], i.first});
			}
		}
	}
	cout << -1 << endl;
}
*/

int n, m;
set<int> inc[30100];
vector< pair<int, int> > adj[30100];
int dist[30100];
bool vis[30100];
priority_queue< pair<int, int> > pq;
int main () {
	cin >> n >> m;
	int bi, pi;
	int start, end;
	for (int i=0; i<m; i++) {
		cin >> bi >> pi;
		inc[bi].insert(pi);
		if (i == 0) start = bi;
		if (i == 1) end = bi;
	}
	for (int i=0; i<n; i++) {
		for (auto j: inc[i]) {
			for (int k=1; k<n; k++) {
				if (i-j*k < 0) break;
				if (inc[i-j*k].find(j) != inc[i-j*k].end()) {
					adj[i].push_back({i-j*k, k});
					break;
				}
				adj[i].push_back({i-j*k, k});
			}
			for (int k=1; k<n; k++) {
				if (i+j*k >= n) break;
				if (inc[i+j*k].find(j) != inc[i+j*k].end()) {
					adj[i].push_back({i+j*k, k});
					break;
				}
				adj[i].push_back({i+j*k, k});
			}
		}
	}
	for (int i=0; i<n; i++) {
		dist[i] = 1e9;
	} 
	dist[start] = 0;
	pq.push({0, start});
	while (pq.size() > 0) {
		pair<int, int> cur = pq.top();
		cur.first = -cur.first;
		pq.pop();
		if (cur.second == end) {
			cout << cur.first << endl;
			return 0;
		}
		if (vis[cur.second]) continue;
		vis[cur.second] = true;
		for (auto i: adj[cur.second]) {
			if (!vis[i.first] && cur.first+i.second < dist[i.first]) {
				dist[i.first] = cur.first+i.second;
				pq.push({-dist[i.first], i.first});
			}
		}
	}
	cout << -1 << endl;
}

Compilation message (stderr)

skyscraper.cpp: In function 'int main()':
skyscraper.cpp:113:3: warning: 'end' may be used uninitialized in this function [-Wmaybe-uninitialized]
   if (cur.second == end) {
   ^~

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