Submission #880966

#	Time	Username	Problem	Language	Result	Execution time	Memory
880966		mychecksedad	Seesaw (JOI22_seesaw)	C++17	1 / 100	1 ms	6644 KiB

seesaw

/* Author : Mychecksdead  */
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define MOD (1000000000+7)
#define MOD1 (998244353)
#define pb push_back
#define all(x) x.begin(), x.end()
#define en cout << '\n'
const int N = 3000+100, M = 1e5+10, K = 52, MX = 30;

int n, a[N];
ll pref[N];
pair<double, double> dp[N][N];
pair<double, double> comp(pair<double, double> x, pair<double, double> y){
  if(x.second - x.first < y.second - y.first) return x;
  return y;
}
void solve(){
  cin >> n;
  for(int i = 1; i <= n; ++i) cin >> a[i];
  pref[0] = 0;
  for(int i = 1; i <= n; ++i) pref[i] = pref[i - 1] + a[i];
  for(int i = 0; i <= n + 1; ++i) for(int j = 0; j <= n + 1; ++j) dp[i][j] = {-1e18, 1e18};
  dp[1][n] = {pref[n] / (double) n, pref[n] / (double) n};
  for(int sz = n - 1; sz >= 0; --sz){
    for(int l = 1; l <= n; ++l){
      int r = l + sz - 1;
      if(r>n) break;
      double pos = (pref[r] - pref[l - 1]) / (double)(r-l+1);
      pair<double, double> v = {min(pos, dp[l][r + 1].first), max(pos, dp[l][r + 1].second)};
      pair<double, double> p = {min(pos, dp[l - 1][r].first), max(pos, dp[l - 1][r].second)};
      dp[l][r] = comp(v, p);
    }
  }
  pair<double, double> ans = {-1e18, 1e18};
  for(int i = 1; i <= n; ++i) ans = comp(ans, dp[i][i]);
  cout << fixed << setprecision(15);
  cout << ans.second - ans.first;
}


int main(){
  cin.tie(0); ios::sync_with_stdio(0);
  int tt = 1, aa;
  // freopen("in.txt", "r", stdin);
  // freopen("out.txt", "w", stdout);
  while(tt--){
    solve();
    en;
  }
  cerr<<"time taken : "<<(float)clock()/CLOCKS_PER_SEC<<" seconds\n";
  return 0;
} 

Compilation message (stderr)

seesaw.cpp: In function 'int main()':
seesaw.cpp:45:15: warning: unused variable 'aa' [-Wunused-variable]
   45 |   int tt = 1, aa;
      |               ^~

• Subtask 1: 1 / 1
• Subtask 2: 0 / 33
• Subtask 3: 0 / 33
• Subtask 4: 0 / 33