Submission #1123430

#	Time	Username	Problem	Language	Result	Execution time	Memory
1123430		VinhLuu	K blocks (IZhO14_blocks)	C++20	100 / 100	121 ms	4504 KiB

blocks

#include <bits/stdc++.h>
//#define int long long
#define ll long long
#define all(lpv) lpv.begin(), lpv.end()
#define fi first
#define se second
#define pot(x, y) lower_bound(x.begin(), x.end(), y) - x.begin() + 1
using namespace std;

typedef pair<int,int> pii;
const int N = 1e5 + 5;
const int mod = 1e9 + 7;

int n, kw;
ll a[N], pf[N], mx[N], f[2][N];

signed main() {
  ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  #define task "v"
  if(fopen(task ".inp","r")){
    freopen(task ".inp","r",stdin);
    freopen(task ".out","w",stdout);
  }

  cin >> n >> kw;
  for(int i = 1; i <= n; i ++) {
    cin >> a[i];
  }

  int pre = 0, nx = 1;
  ll _tmp = 0;
  for(int i = 1; i <= n; i ++) {
    _tmp = max(_tmp, a[i]);
    f[pre][i] = _tmp;
  }
  pf[0] = 1e16;
  for(int k = 2; k <= kw; k ++) {
    stack<int> st;
    for(int i = k; i <= n; i ++) {
      mx[i] = f[pre][i - 1];
      while(!st.empty() && a[st.top()] <= a[i]) {
        mx[i] = min(mx[i], mx[st.top()]);
        st.pop();
      }
      int last = (!st.empty() ? st.top() : 0);
      pf[i] = min(mx[i] + a[i], pf[last]);
      f[nx][i] = pf[i];
      st.push(i);
    }
    swap(pre, nx);
  }
  cout << f[pre][n];
}

Compilation message (stderr)

blocks.cpp: In function 'int main()':
blocks.cpp:21:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |     freopen(task ".inp","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
blocks.cpp:22:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   22 |     freopen(task ".out","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 18 / 18
• Subtask 3: 21 / 21
• Subtask 4: 47 / 47