线段树模板

#include <bits/stdc++.h>
using namespace std;
 
int C[1005][1005];
int main()
{
	C[0][0] = 1;
	for (int i = 1; i <= 1000; i++)
	{
		C[i][0] = 1;
		for (int j = 1; j <= 1000; j++)
			C[i][j] = C[i - 1][j - 1] + C[i - 1][j]; 
	}
	
	cout << C[4][3] << endl;
	
	return 0;
}