Submission #866981

#TimeUsernameProblemLanguageResultExecution timeMemory
866981HossamHero7The short shank; Redemption (BOI21_prison)C++14
0 / 100
1466 ms12892 KiB
#include <bits/stdc++.h> using namespace std; typedef long long ll; #define endl '\n' const int N = 75005; int P[N][20] , dp[N][2] , costt[N][20]; int t; vector<int> v; int cost(int l,int r){ int ret = 0; int cur = l; for(int k=19;k>=0;k--){ if(P[cur][k] <= r) { ret += costt[cur][k]; cur = P[cur][k]; } } ret += min(max(t-v[cur]+1,0),r-cur+1); return ret; } void calc(int l,int r,int opt1,int opt2,int k){ if(l > r) return; int i = l + r >> 1; pair<int,int> opt{1e9,-1}; for(int p=opt1;p<=min(opt2,r);p++){ if(p) opt = min(opt,{dp[p-1][k-1&1]+cost(p,i),p}); else opt = min(opt,{cost(0,i),p}); } dp[i][k&1] = opt.first; calc(l,i-1,opt1,opt.second,k); calc(i+1,r,opt.second,opt2,k); } void solve(){ int n,d; cin>>n>>d>>t; v.resize(n); for(auto &i:v) cin>>i; vector<int> starts; for(int i=n-1;i>=0;i--){ while(starts.size()){ int a = starts.back(); if(v[a] >= v[i]+(a-i)) starts.pop_back(); else break; } P[i][0] = (starts.size() ? starts.back() : n); costt[i][0] = min(max(t-v[i]+1,0),P[i][0] - i); starts.push_back(i); } for(int k=1;k<20;k++){ for(int i=0;i<n;i++){ if(P[i][k-1] == n) P[i][k] = n; else P[i][k] = P[P[i][k-1]][k-1]; costt[i][k] = costt[i][k-1] + costt[P[i][k-1]][k-1]; } } int lst = v[0]; int prefix = (lst <= t); dp[0][0] = prefix; for(int j=1;j<n-1;j++) { if(v[j] > lst) lst ++; else lst = v[j]; prefix += (lst <= t); dp[j][0] = prefix; } for(int k=1;k<=d;k++) calc(0,n-1,0,n-1,k); cout<<dp[n-1][d&1]<<endl; } int main(){ ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); int t=1; //cin>>t; while(t--){ solve(); } return 0; }

Compilation message (stderr)

prison.cpp: In function 'void calc(int, int, int, int, int)':
prison.cpp:23:15: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   23 |     int i = l + r >> 1;
      |             ~~^~~
prison.cpp:26:39: warning: suggest parentheses around '-' in operand of '&' [-Wparentheses]
   26 |         if(p) opt = min(opt,{dp[p-1][k-1&1]+cost(p,i),p});
      |                                      ~^~
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