다리 놓기

#include <iostream> #include <vector> #define endl "\n" int T, N, M, ans; std::vector<std::vector<int> >save; void input_faster() { std::ios_base::sync_with_stdio(false); std::cin.tie(0); std::cout.tie(0); } void input() { input_faster(); std::cin >> T; save.resize(30, std::vector<int>(30)); } int combination(int y, int x) { if (save[y][x] != 0) return (save[y][x]); if (x == y || x == 0) return (1); save[y][x] = combination(y - 1, x - 1) + combination(y - 1, x); return (save[y][x]); } void solve() { int x, y; std::cin >> x >> y; if (save[y][x]) ans = save[y][x]; ans = combination(y, x); } void print_val() { std::cout << ans << endl; } int main() { input(); while (T--) { ans = 0; solve(); print_val(); } return (0); }