Submission #671136

#	Time	Username	Problem	Language	Result	Execution time	Memory
671136		NothingXD	Jakarta Skyscrapers (APIO15_skyscraper)	C++14	57 / 100	1091 ms	74576 KiB

skyscraper

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

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
/*typedef __uint128_t L;
struct FastMod {
  ull b, m;
  FastMod(ull b) : b(b), m(ull((L(1) << 64) / b)) {}
  ull reduce(ull a) {
    ull q = (ull)((L(m) * a) >> 64);
    ull r = a - q * b; // can be proven that 0 <= r < 2*b
    return r >= b ? r - b : r;
  }
};
FastMod FM(2);*/
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
	cerr << " " << H;
	debug_out(T...);
}

#define debug(...) cerr << "(" << #__VA_ARGS__ << "):", debug_out(__VA_ARGS__)
#define all(x) x.begin(), x.end()
#define MP(x, y) make_pair(x, y)
#define F first
#define S second

//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int maxn = 3e4 + 10;

int n, m, a[maxn], b[maxn];
unordered_map<int,bool> mark;
unordered_map<int,int> h;
vector<int> val[maxn];

int getidx(pii x){
	return x.F * n + x.S;
}

void bfs(pii st){
	h[getidx(st)] = 0;
	mark[getidx(st)] = true;
	deque<pii> q;
	q.push_back(st);
	while(!q.empty()){
		int v = q.front().F, k = q.front().S;
		int ptr = getidx({v, k});
		q.pop_front();
		for (auto x: val[v]){
			int u = getidx({v, x});
			if (!mark[u] || h[u] > h[ptr]){
				h[u] = h[ptr];
				mark[u] = true;
				q.push_front({v, x});
			}
		}
		val[v].clear();
		int u = getidx({v-k, k});
		if (v - k >= 0 && !mark[u]){
			h[u] = h[ptr] + 1;
			mark[u] = true;
			q.push_back({v-k, k});
		}
		u = getidx({v+k, k});
		if (v + k < n && !mark[u]){
			h[u] = h[ptr] + 1;
			mark[ptr] = true;
			q.push_back({v+k, k});
		}
	}
}

int main(){
	ios_base::sync_with_stdio(false); cin.tie(0);

	cin >> n >> m;

	for (int i = 1; i <= m; i++){
		cin >> a[i] >> b[i];
		if (b[i] < n) val[a[i]].push_back(b[i]);
	}
	for (int i = 0; i < n; i++){
		val[i].push_back(0);
	}

	bfs({a[1], b[1]});

	cout << (!mark[getidx({a[2], 0})]? -1: h[getidx({a[2], 0})]) << '\n';

	return 0;
}

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