Submission #539056

#	Time	Username	Problem	Language	Result	Execution time	Memory
539056		alextodoran	Calvinball championship (CEOI15_teams)	C++17	100 / 100	244 ms	544 KiB

teams

/**
 ____ ____ ____ ____ ____
||a |||t |||o |||d |||o ||
||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|

**/

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int N_MAX = 10000;

const int MOD = (int) 1e6 + 7;

int N;
int A[N_MAX + 2];

int first[N_MAX + 2];
int teamsPref[N_MAX + 2];

int dp[2][N_MAX + 2];

int main () {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    cin >> N;
    for (int i = 1; i <= N; i++) {
        cin >> A[i];
        teamsPref[i] = teamsPref[i - 1];
        if (first[A[i]] == 0) {
            first[A[i]] = i;
            teamsPref[i]++;
        }
    }

    int answer = 0;
    fill(dp[1] + 1, dp[1] + N + 1, 1);
    for (int i = N; i >= 1; i--) {
        for (int k = 0; k < i; k++) {
            // dp[i][k] = number of assignments of i..N, when there are already k teams opened
            dp[0][k] = ((ll) dp[1][k] * k + dp[1][k + 1]) % MOD;
        }
        // Try any possible value of B[i]<A[i] and count the assignments for the rest
        for (int x = 1; x < A[i]; x++) {
            answer += dp[1][teamsPref[i - 1] + (i < first[x])];
            if (answer >= MOD) {
                answer -= MOD;
            }
        }
        swap(dp[0], dp[1]);
    }
    answer++;
    cout << answer << "\n";

    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 10 / 10
• Subtask 5: 10 / 10
• Subtask 6: 10 / 10
• Subtask 7: 10 / 10
• Subtask 8: 10 / 10
• Subtask 9: 10 / 10
• Subtask 10: 10 / 10