Submission #118396

#	Time	Username	Problem	Language	Result	Execution time	Memory
118396		silxikys	Calvinball championship (CEOI15_teams)	C++14	0 / 100	52 ms	8500 KiB

teams

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

const int maxn = 1e4+4, M = 1e9+7;
int n, a[maxn];

void madd(int& a, int b) {
    a = (a+b) % M;
}
int mult(int a, int b) {
    return (1LL*a*b) % M;
}

/*
 * f(i,j) = # combinations, w/ i spaces left, that can be up to j
 * f(i,j) = j*f(i-1,j) + f(i-1,j+1)
 * f(1,x) = x
 * f(2,x) = j*x+x+1 = (j+1)*x+1
 *
 * */

int dp[1003][1003];
int sum[maxn];

int br = 0;
void DFS(vector<int> v) {
    if (v.size() == n) {
        bool poss = true;
        int biggestSeen = 0;
        for (int i: v) {
            if (i > biggestSeen+1) {
                poss = false;
                break;
            }
            biggestSeen = max(biggestSeen,i);
        }
        if (poss) {
            br++;
            /*
            for (int i: v) {
                cout << i << ' ';
            }
            cout << '\n';
            */
        }
    }
    else {
        for (int j = 1; j <= n; j++) {
            v.push_back(j);
            DFS(v);
            v.pop_back();
        }
    }
}

int brute() {
    vector<int> v;
    DFS(v);
    return br;
}

int main()
{
    //ios_base::sync_with_stdio(false); cin.tie(0);
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    
    for (int i = 0; i <= n; i++) {
        dp[1][i] = i;
        //cout << dp[1][i] << ' ';
    }
    //cout << '\n';
    for (int i = 2; i <= n; i++) {
        for (int j = 1; j <= n+1-i; j++) {
            dp[i][j] = (j-1)*dp[i-1][j] + dp[i-1][j+1];
            //printf("[%d][%d]: %d\n",i,j,dp[i][j]);
            //cout << dp[i][j] << ' ';
            madd(sum[i],dp[i][j]);
        }
        //cout << '\n';
    }
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        madd(ans,dp[n+1-i][a[i]-1]);
        //cout << ans << '\n';
        //curr = dp[n+1-i][a[i]];
    }
    madd(ans,1);
    cout << dp[n][1] << '\n';
    //cout << "brute: " << ' ' << brute() << '\n';
}

Compilation message (stderr)

teams.cpp: In function 'void DFS(std::vector<int>)':
teams.cpp:28:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if (v.size() == n) {
         ~~~~~~~~~^~~~

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10