Submission #554722

#	Time	Username	Problem	Language	Result	Execution time	Memory
554722		kwongweng	Jakarta Skyscrapers (APIO15_skyscraper)	C++17	100 / 100	719 ms	24672 KiB

skyscraper

/*
Solution for APIO 2015 - Skyscrapper
Tags : sqrt decomposition
*/

#include <bits/stdc++.h>
using namespace std;
 
#pragma GCC target ("avx2")
#pragma GCC optimization ("Ofast")
#pragma GCC optimization ("unroll-loops")
 
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef long double ld;
typedef pair<ll, ll> pll;
#define FOR(i, a, b) for(int i = a; i < b; i++)
#define ROF(i, a, b) for(int i = a; i >= b; i--)
#define ms memset
#define pb push_back
#define fi first
#define se second
 
ll MOD = 1000000007;
 
ll power(ll base, ll n){
	if (n == 0) return 1;
	if (n == 1) return base;
	ll halfn = power(base, n/2);
	if (n % 2 == 0) return (halfn * halfn) % MOD;
	return (((halfn * halfn) % MOD) * base) % MOD;
}
 
ll inverse(ll n){
	return power(n, MOD-2);
}
 
ll add(ll a, ll b){
	return (a+b) % MOD;
}
 
ll mul(ll a, ll b){
	a %= MOD;
	return (a*b) % MOD;
}
 
ll gcd(ll a, ll b){
    if (a == 1) return 1;
    if (a == 0) return b;
    return gcd(b%a, a);
}
 
void solve(){
    int n, m; cin >> n>> m;
    vi doge[n];
    int dest; int start;
    FOR(i,0,m){
        int b, p; cin >> b >> p;
        doge[b].pb(p);
        if (i==0) start = b;
        if (i==1) dest = b;
    }
    int B = floor(sqrt(n));
    set<pair<int, ii>> st;
    int dist[n][B+1];
    FOR(i,0,n){
        FOR(j,0,B+1){
            dist[i][j] = MOD;
        }
    }
    dist[start][0] = 0;
    st.insert({dist[start][0], {start, 0}});
    while (!st.empty()){
        auto node = *st.begin();
        st.erase(st.begin());
        int u = node.se.fi, w = node.se.se;
        if (w==0){
            for (int p : doge[u]){
                if (p > B){
                    int cur = u+p;
                    while (cur<n){
                        if (dist[cur][0] <= dist[u][w] + (cur-u)/p){
                            cur += p; continue;
                        }
                        if (dist[cur][0] != MOD){
                            st.erase({dist[cur][0], {cur, 0}});
                        }
                        dist[cur][0] = dist[u][w] + (cur-u)/p;
                        st.insert({dist[cur][0], {cur, 0}});
                        cur += p;
                    }
                    cur = u-p;
                    while (cur >= 0){
                        if (dist[cur][0] <= dist[u][w] + (u-cur)/p){
                            cur -= p; continue;
                        }
                        if (dist[cur][0] != MOD){
                            st.erase({dist[cur][0], {cur, 0}});
                        }
                        dist[cur][0] = dist[u][w] + (u-cur)/p;
                        st.insert({dist[cur][0], {cur, 0}});
                        cur -= p;
                    }
                    continue;
                }
                if (dist[u][p] <= dist[u][w]){
                    continue;
                }
                if (dist[u][p] != MOD){
                    st.erase({dist[u][p], {u, p}});
                }
                dist[u][p] = dist[u][w];
                st.insert({dist[u][p], {u, p}});
            }
            continue;
        }
        if (dist[u][0] > dist[u][w]){
            if (dist[u][0] != MOD){
                st.erase({dist[u][0], {u, 0}});
            }
            dist[u][0] = dist[u][w];
            st.insert({dist[u][0], {u, 0}});
        }
        if (u+w < n && dist[u+w][w] > dist[u][w] + 1){
            if (dist[u+w][w] != MOD){
                st.erase({dist[u+w][w], {u+w, w}});
            }
            dist[u+w][w] = dist[u][w] + 1;
            st.insert({dist[u+w][w], {u+w, w}});
        }
        if (u-w >= 0 && dist[u-w][w] > dist[u][w] + 1){
            if (dist[u-w][w] != MOD){
                st.erase({dist[u-w][w], {u-w, w}});
            }
            dist[u-w][w] = dist[u][w] + 1;
            st.insert({dist[u-w][w], {u-w, w}});
        }
    }
    if (dist[dest][0] == MOD){
        cout << -1;
        return;
    }
    cout << dist[dest][0];
}
 
int main() {
    ios::sync_with_stdio(false);
    int TC = 1;
    //cin >> TC;
    FOR(i, 1, TC+1){
        //cout << "Case #" << i << ": ";
        solve();
    }
}

Compilation message (stderr)

skyscraper.cpp:10: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
   10 | #pragma GCC optimization ("Ofast")
      | 
skyscraper.cpp:11: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
   11 | #pragma GCC optimization ("unroll-loops")
      | 
skyscraper.cpp: In function 'void solve()':
skyscraper.cpp:73:20: warning: 'start' may be used uninitialized in this function [-Wmaybe-uninitialized]
   73 |     dist[start][0] = 0;
      |     ~~~~~~~~~~~~~~~^~~
skyscraper.cpp:141:21: warning: 'dest' may be used uninitialized in this function [-Wmaybe-uninitialized]
  141 |     if (dist[dest][0] == MOD){
      |         ~~~~~~~~~~~~^

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