Submission #856923

#TimeUsernameProblemLanguageResultExecution timeMemory
856923Tudy006Climbers (RMI18_climbers)C++14
100 / 100
151 ms195932 KiB
#include <bits/stdc++.h> #pragma GCC optimize("Ofast,unroll-loops") using namespace std; const int NMAX = 5000; const long long INF = 1e18; priority_queue <pair<long long, pair<int, int>>> pq; inline long long modul( long long x ) {return x < 0 ? -x : x;} inline bool between( int a, int b, int c ) {return ( a <= b && b <= c ) || ( a >= b && b >= c );} long long dist[NMAX][NMAX - 1]; inline void update( int i, int j, long long d ) { if ( d < dist[i][j] ) { dist[i][j] = d; pq.push( { -d, { i, j } } ); } } int main() { int n; cin >> n; vector <int> v; for ( int i = 1, x; i <= n; i ++ ) { cin >> x; while ( v.size() >= 2 && between( v[v.size() - 2], v[v.size() - 1], x ) ) v.pop_back(); v.push_back( x ); } n = v.size(); for ( int i = 0; i <= n - 1; i ++ ) { for ( int j = 0; j <= n - 2; j ++ ) { dist[i][j] = INF; } } dist[0][n - 2] = 0; pq.push( { 0, {0, n - 2} } ); while ( !pq.empty() ) { auto p = pq.top(); int i = p.second.first, j = p.second.second; long long d = dist[i][j]; if ( -p.first == d ) { if ( i == j || i == j + 1 ) { cout << d << '\n'; return 0; } if ( i + 1 < n && between( v[j], v[i + 1], v[j + 1] ) ) { update( i + 1, j, d + modul( v[i] - v[i + 1] ) ); } if ( i - 1 >= 0 && between( v[j], v[i - 1], v[j + 1] ) ) { update( i - 1, j, d + modul( v[i] - v[i - 1] ) ); } if ( i + 1 < n && between( v[i], v[j], v[i + 1] ) ) { update( j, i, d + modul( v[i] - v[j] ) ); } if ( i - 1 >= 0 && between( v[i], v[j], v[i - 1] ) ) { update( j, i - 1, d + modul( v[i] - v[j] ) ); } if ( i + 1 < n && between( v[i], v[j + 1], v[i + 1] ) ) { update( j + 1, i, d + modul( v[i] - v[j + 1] ) ); } if ( i - 1 >= 0 && between( v[i], v[j + 1], v[i - 1] ) ) { update( j + 1, i - 1, d + modul( v[i] - v[j + 1] ) ); } } pq.pop(); } cout << "NO\n"; return 0; }
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