CCC 2015 J5 π-day

    1#include <bits/stdc++.h>
    2using namespace std;
    3using ll = long long;
    4using i128 = __int128;
    5const int inf = 1e9;
    6const ll INF = 2e18; //❄️
    7int main() {
    8    ios::sync_with_stdio(0); cin.tie(0); 
    9    int n, k; cin >> n >> k;
    10    if (n == 1 || n == k) {
    11        cout << 1 << '\n';
    12        return 0;
    13    }
    14    vector<vector<int>> dp(k + 1, vector<int>(n + 1));
    15    dp[0][0] = 1;
    16    for (int i = 1; i <= k; i++) {
    17        for (int j = 1; j <= n; j++) {
    18            dp[i][j] = dp[i - 1][j - 1] + (j >= i ? dp[i][j -i ] : 0);
    19        }
    20    }
    21    cout << dp[k][n] << '\n';
    22    return 0;
    23}