Submission #160924

#	Time	Username	Problem	Language	Result	Execution time	Memory
160924		nvmdava	Jakarta Skyscrapers (APIO15_skyscraper)	C++17	0 / 100	3 ms	1016 KiB

skyscraper

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ff first
#define ss second
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#define N 2005
#define INF 0x3f3f3f3f3f3f3f3f
#define MOD 1000000007LL

vector<int> pl[30005];
bool in[N];

map<pair<int, int>, int> ans;

queue<pair<int, int > > q;

void insert(int s, int v){
	if(in[s]) return;
	in[s] = 1;

	for(auto& x : pl[s]){
		q.push({s, x});
		ans[{s, x}] = v;
	}
}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n, m, s, e;
    cin>>n>>m;
    for(int i = 1, b, p; i <= m; i++){
    	cin>>b>>p;
    	pl[b].push_back(p);
    	if(i == 1)
    		s = b;
    	else if(i == 2)
    		e = b;
    }
    if(s == e){
    	cout<<0;
    	return 0;
    }
    insert(s, 0);
    while(!q.empty()){
    	int b = q.front().ff;
    	int p = q.front().ss;
    	int v = ans[q.front()];
    	q.pop();
    	if(v == -1)
    		continue;
    	if(b >= p){
    		if(b - p == e){
    			cout<<v + 1;
    			return 0;
    		}
    		if(ans.find({b - p, p}) == ans.end()){
    			insert(b - p, v + 1);
    			q.push({b - p, p});
    			ans[{b - p, p}] = v + 1;
    		}
    	}
    	if(b + p < n){
 			if(b + p == e){
 				cout<<v + 1;
 				return 0;
 			}
    		if(ans.find({b + p, p}) == ans.end()){
    			insert(b + p, v + 1);
    			q.push({b + p, p});
    			ans[{b + p, p}] = v + 1;
    		}
    	}
    	ans[{b, p}] = -1;
    }
}

Compilation message (stderr)

skyscraper.cpp: In function 'int main()':
skyscraper.cpp:55:7: warning: 'e' may be used uninitialized in this function [-Wmaybe-uninitialized]
       if(b - p == e){
       ^~
skyscraper.cpp:32:15: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
     int n, m, s, e;
               ^

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