백준 소스코드 [C++] 2407 조합

www.acmicpc.net/problem/2407

2407번: 조합

백준 소스코드 [C++] 2407 조합

#include <iostream>
#include <algorithm>
#include <queue>
#include <string.h>
#include <limits.h>
#include <vector>
#include <math.h>
#include <stack>
#include <bitset>
#include <string>
typedef long long ll;
using namespace std;
string arr[101][101];
string bigadd(string a, string b) {
	string c;
	int as, bs;
	int bit = 0;
	while (!a.empty() && !b.empty()) {
		as = a.back() - '0'; bs = b.back() - '0';
		c = (char)(((as + bs + bit) % 10) + '0') + c;
		bit = (as + bs + bit) / 10;
		a.pop_back();b.pop_back();
	}
	while (!a.empty()) {
		as = a.back() - '0';
		c = (char)(((as + bit) % 10) + '0') + c;
		bit = (as + bit) / 10;
		a.pop_back();
	}
	while (!b.empty()) {
		bs = b.back() - '0';
		c = (char)(((bs + bit) % 10) + '0') + c;
		bit = (bs + bit) / 10;
		b.pop_back();
	}
	if (bit == 1)c = (char)(bit + '0') + c;
	return c;
}
string combination(int n, int m) {
	if (arr[n][m]!="") return arr[n][m];
	else return arr[n][m]=bigadd(combination(n - 1, m - 1), combination(n - 1, m));
}

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	int n, m;
	cin >> n >> m;
	for (int i = 1;i <= 100;i++)arr[i][i]=arr[i][0] = '1';
	cout << combination(n, m);
	return 0;
}