Submission #220249

#	Time	Username	Problem	Language	Result	Execution time	Memory
220249		Nightlight	Split the sequence (APIO14_sequence)	C++14	100 / 100	1285 ms	81408 KiB

sequence

#include <bits/stdc++.h>
using namespace std;

int N, M;
int A[100005];
long long pre[100005];
int opt[205][100005];
long long dp[2][100005];
int ans[105];

long long cost(int l, int r) {
  return (pre[r] - pre[l - 1]) * pre[l - 1];
}

void dnc(int K, int l, int r, int kl, int kr) {
  if(l > r) return;
  int mid = (l + r) >> 1;
  long long best = -1e18, tmp;
  int id = 0;
  for(int i = min(mid, kr); i >= kl; i--) {
    tmp = dp[!(K & 1)][i - 1] + cost(i, mid);
    if(tmp > best) {
      best = tmp, id = i;
    }
  }
  dp[K & 1][mid] = best;
  opt[K][mid] = id;
  
  dnc(K, l, mid - 1, kl, id);
  dnc(K, mid + 1, r, id, kr);
}

void backtrack(int K, int now) {
  ans[K] = now;
  if(K == 0) return;
  backtrack(K - 1, opt[K][now] - 1);
}

int main() {
//  freopen("inp", "r", stdin);
  scanf("%d %d", &N, &M);
  for(int i = 1; i <= N; i++) {
    scanf("%d", &A[i]);
    pre[i] = A[i] + pre[i - 1];
  }
  for(int k = 1; k <= M; k++) {
    dnc(k, k + 1, N, k + 1, N);
  }
  long long best = 0, id = 0;
  backtrack(M, N);
  printf("%lld\n", dp[M & 1][N]);
  for(int i = 0; i < M; i++) {
    printf("%d ", ans[i]);
  }
}

Compilation message (stderr)

sequence.cpp: In function 'int main()':
sequence.cpp:49:13: warning: unused variable 'best' [-Wunused-variable]
   long long best = 0, id = 0;
             ^~~~
sequence.cpp:49:23: warning: unused variable 'id' [-Wunused-variable]
   long long best = 0, id = 0;
                       ^~
sequence.cpp:41:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &N, &M);
   ~~~~~^~~~~~~~~~~~~~~~~
sequence.cpp:43:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &A[i]);
     ~~~~~^~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 11 / 11
• Subtask 3: 11 / 11
• Subtask 4: 17 / 17
• Subtask 5: 21 / 21
• Subtask 6: 29 / 29