Submission #37540

#	Time	Username	Problem	Language	Result	Execution time	Memory
37540		Talant	Split the sequence (APIO14_sequence)	C++11	100 / 100	1213 ms	82880 KiB

sequence

#include <bits/stdc++.h>

using namespace std;

#define pb push_back
#define ll long long

const int N = (int)1e5 + 7;
const ll inf = (ll)1e18 + 7;

ll dp[2][N];
ll pref[N];
int backtrack[201][N];
int n;

ll calc (int l, int r) {
    return pref[l] * (pref[r] - pref[l]);
}

void div (int k, int l, int r, int optl, int optr) {
    if (l > r) return;
    int mid = (l + r) >> 1;
    dp[k & 1][mid] = 0;
    int opt = optl;
    for (int i = optl; i <= min(mid - 1, optr); i++) {
        ll cur = dp[k & 1 ^ 1][i] + calc(i, mid);
        if (cur >= dp[k & 1][mid]) {
            dp[k & 1][mid] = cur;
            opt = i;
        }
    }
    backtrack[k][mid] = opt;
    div(k, l, mid - 1, optl, opt);
    div(k, mid + 1, r, opt, optr);
}

main () {
    int k; scanf ("%d %d", &n, &k);
    for (int i = 1; i <= n; i++) {
        scanf ("%lld", pref + i);
        pref[i] += pref[i - 1];
    }
    for (int i = 1; i <= k; i++)
        div(i, 1, n, 1, n - 1);

    printf ("%lld\n", dp[k & 1][n]);
    while (k > 0) {
        printf ("%d ", backtrack[k][n]);
        n = backtrack[k][n];
        k--;
    }
}

Compilation message (stderr)

sequence.cpp: In function 'void div(int, int, int, int, int)':
sequence.cpp:26:23: warning: suggest parentheses around arithmetic in operand of '^' [-Wparentheses]
         ll cur = dp[k & 1 ^ 1][i] + calc(i, mid);
                       ^
sequence.cpp: At global scope:
sequence.cpp:37:7: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main () {
       ^
sequence.cpp: In function 'int main()':
sequence.cpp:38:35: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     int k; scanf ("%d %d", &n, &k);
                                   ^
sequence.cpp:40:33: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf ("%lld", pref + 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