Submission #1043918

#	Time	Username	Problem	Language	Result	Execution time	Memory
1043918		Alihan_8	Sky Walking (IOI19_walk)	C++17	0 / 100	383 ms	79048 KiB

walk

#include "walk.h"

#include <bits/stdc++.h>

using namespace std;

#define pb push_back
#define ar array
#define all(x) x.begin(), x.end()
#define ln '\n'

using i64 = long long;

template <class F, class S>
bool chmin(F &u, const S &v){
	bool flag = false;
	
	if ( u > v ){
		u = v; flag |= true;
	}
	
	return flag;
}

const i64 inf = 1e15;

long long min_distance(std::vector<int> x, std::vector<int> h, std::vector<int> l, std::vector<int> r, std::vector<int> y, int s, int g) {
	int n = x.size(), m = l.size();
	
	vector <vector<ar<int,3>>> H(n + 1);
	
	{ // shifting y
		y.pb(0);
		for ( int i = m; i > 0; i-- ){
			y[i] = y[i - 1];
		} y[0] = 0;
	}
	
	for ( int i = 1; i <= m; i++ ){
		H[l[i - 1]].pb({1, y[i], i});
		H[r[i - 1] + 1].pb({0, y[i], i});
	}
	
	set <pair<int,int>> st;
	
	vector <vector<int>> a(n, {0}), mp(m + 1);
	
	auto V = a;
	
	for ( int i = 0; i < n; i++ ){
		for ( auto &[t, y, j]: H[i] ){
			if ( t > 0 ){
				st.insert({y, j});
			} else st.erase({y, j});
		}
		
		auto it = st.begin();
		
		while ( it != st.end() && it -> first <= h[i] ){
			a[i].pb(it -> second);
			V[i].pb(it -> first);
			mp[it -> second].pb(i);
			it = next(it);
		}
	}
	
	vector <vector<i64>> dp(n);
	vector <vector<int>> id(n);
	
	for ( int i = 0; i < n; i++ ){
		sort(all(a[i]), [&](int &u, int &v){
			return y[u] < y[v];
		});
		
		sort(all(V[i]));
		
		int s = a[i].size();
		dp[i].resize(s, inf);
		id[i].resize(s);
		
		for ( int j = 1; j < s; j++ ){
			int x = a[i][j];
			
			id[i][j] = lower_bound(all(mp[x]), i) - mp[x].begin();
		}
	}
	
	dp[s][0] = 0;
	
	priority_queue <ar<i64,3>> q;
	
	q.push({0, s, 0});
	
	while ( !q.empty() ){
		auto [val, u, j] = q.top();
		q.pop();
		
		if ( -val != dp[u][j] ) continue;
		
		if ( j != 0 ){ // using skywalk j
			int t = a[u][j];
			
			for ( auto i: {id[u][j] - 1, id[u][j] + 1} ){
				
				if ( i < 0 || i >= (int)mp[t].size() ){
					continue;
				}
				
				int v = mp[t][i], nxt = lower_bound(all(V[v]), y[t]) - V[v].begin();
				
				if ( a[v][nxt] != t ){
					assert(false); return -2;
				}
				
				if ( chmin(dp[v][nxt], dp[u][j] + abs(x[v] - x[u])) ){
					q.push({-dp[v][nxt], v, nxt});
				}
			}
		}
		
		for ( auto i: {j + 1, j - 1} ){
			if ( i < 0 || i >= (int)dp[u].size() ){
				continue;
			}
			
			if ( chmin(dp[u][i], dp[u][j] + abs(y[a[u][j]] - y[a[u][i]])) ){
				q.push({-dp[u][i], u, i});
			}
		}
	}
	
	i64 ans = dp[g][0];
	
	if ( ans == inf ){
		ans = -1;
	}
	
	return ans;
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 14
• Subtask 3: 0 / 15
• Subtask 4: 0 / 18
• Subtask 5: 0 / 43