Submission #281786

#	Time	Username	Problem	Language	Result	Execution time	Memory
281786		srvlt	Jakarta Skyscrapers (APIO15_skyscraper)	C++14	100 / 100	712 ms	144892 KiB

skyscraper

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define pb push_back
#define all(x) begin(x), end(x)
#define SZ(x) (int)(x).size()
#define cps(x) sort(all(x)), (x).erase(unique(all(x)), end(x))
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int n0 = 30003, inf = 1e9;
int n, m, num, ind[n0];
vector <int> rem[n0], vec[n0], b, d, out[n0];
vector <int> g1, g2, g3;
deque <int> q;

void relax0(int v, int u) {
	if (d[u] > d[v]) {
		d[u] = d[v];
		q.push_front(u);
	}
}

void relax1(int v, int u) {
	if (d[u] > d[v] + 1) {
		d[u] = d[v] + 1;
		q.pb(u);
	}
}

void bfs(int x) {
	q.pb(x);
	for (int i = 0; i < num; i++)
		d[i] = inf;
	d[x] = 0;
	while (!q.empty()) {
		int v = q.front();
		q.pop_front();
		if (v < n) {
			for (int i : out[v]) relax0(v, i);
		}	else {
			if (g1[v]) relax1(v, v - 1);
			if (g2[v]) relax1(v, v + 1);
			relax0(v, g3[v]);
		}
	}
}

int main() {
	ios_base::sync_with_stdio(false), cin.tie(NULL);
	cin >> n >> m;
	int s, f;
	for (int i = 0; i < m; i++) {
		int B, P;
		cin >> B >> P;
		if (i == 0) s = B;
		if (i == 1) f = B;
		vec[P].pb(B);
		rem[P].pb(B % P);
	}
	num = n;
	for (int i = 1; i < n0; i++) {
		cps(rem[i]);
		for (int j : rem[i])
			num += ((n - 1) - j) / i + 1;
	}
	assert(num < 7500000);
	b.resize(num), d.resize(num);
	g1.resize(num), g2.resize(num), g3.resize(num);
	int cur = n;
	for (int i = 1; i < n0; i++) {
		for (int j : rem[i]) {
			for (int k = j; k < n; k += i) {
				g1[cur] = (k != j);
				g2[cur] = (k + i < n);
				g3[cur] = k;
				ind[k] = cur++;
			}
		}
		for (int j : vec[i])
			out[j].pb(ind[j]);
	}
	bfs(s);
	if (d[f] == inf) cout << -1;
	else cout << d[f];
}

Compilation message (stderr)

skyscraper.cpp: In function 'int main()':
skyscraper.cpp:84:9: warning: 'f' may be used uninitialized in this function [-Wmaybe-uninitialized]
   84 |  if (d[f] == inf) cout << -1;
      |         ^
skyscraper.cpp:83:5: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
   83 |  bfs(s);
      |  ~~~^~~

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