Add function that computes a nCr table.

Author: yassin64b

Math/Combinations/nCr_table.cpp

@@ -0,0 +1,33 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+constexpr int MOD = 1000000007;
+
+// compute a table ncr[i][j] = C(i, j) % MOD for i <= n, j <= m
+vector<vector<int>> ncr_table(int n, int m) {
+    vector<vector<int>> ncr(n + 1, vector<int>(m + 1, 0));
+    for(int i = 0; i <= n; i++) {
+        ncr[i][0] = 1;
+    }
+    for(int i = 1; i <= n; i++) {
+        for(int j = 1; j <= m && j <= i; j++) {
+            ncr[i][j] = (ncr[i - 1][j - 1] + ncr[i - 1][j]) % MOD;
+        }
+    }
+    return ncr;
+}
+
+int main() {
+	int n, m;
+	cin >> n >> m;
+	vector<vector<int>> ncr(ncr_table(n, m));
+	for (int i = 1; i <= n; ++i) {
+		for (int j = 1; j <= m; ++j) {
+			cout << ncr[i][j] << " ";
+		}
+		cout << "\n";
+	}
+	return 0;
+}