[#11] Add abc202 codes

Author: zeikar

ABC_202_A.cpp

@@ -0,0 +1,10 @@
+#include <iostream>
+using namespace std;
+
+int main() {
+	int a, b, c;
+
+	cin >> a >> b >> c;
+
+	cout << 21 - (a + b + c) << endl;
+}

ABC_202_B.cpp

@@ -0,0 +1,23 @@
+#include <iostream>
+#include <string>
+using namespace std;
+
+int main() {
+	string s;
+	cin >> s;
+	for (int i = s.size() - 1; i >= 0; i--)
+	{
+		if (s[i] == '9') {
+			cout << 6;
+		}
+		else if (s[i] == '6')
+		{
+			cout << 9;
+		}
+		else
+		{
+			cout << s[i];
+		}
+	}
+	cout << endl;
+}

ABC_202_C.cpp

@@ -0,0 +1,35 @@
+#include <iostream>
+using namespace std;
+
+long long a[100000], b[100000], c[100000];
+long long acnt[100001], bcnt[100000];
+
+int main() {
+	int n;
+	cin >> n;
+	for (int i = 0; i < n; i++)
+	{
+		cin >> a[i];
+		a[i]--;
+		acnt[a[i]]++;
+	}
+	for (int i = 0; i < n; i++)
+	{
+		cin >> b[i];
+		b[i]--;
+	}
+	for (int i = 0; i < n; i++)
+	{
+		cin >> c[i];
+		c[i]--;
+		bcnt[b[c[i]]]++;
+	}
+
+	long long result = 0;
+	for (int i = 0; i < n; i++)
+	{
+		result += (acnt[i] * bcnt[i]);
+	}
+
+	cout << result << endl;
+}

ABC_202_D.cpp

@@ -0,0 +1,64 @@
+#include <iostream>
+#include <string>
+using namespace std;
+
+long long C[61][61];
+
+// Returns value of Binomial Coefficient C(n, k)
+long long binomialCoeff(int n, int k)
+{
+	int i, j;
+
+	// Caculate value of Binomial Coefficient
+	// in bottom up manner
+	for (i = 0; i <= n; i++) {
+		for (j = 0; j <= min(i, k); j++) {
+			// Base Cases
+			if (j == 0 || j == i)
+				C[i][j] = 1;
+
+			// Calculate value using previously
+			// stored values
+			else
+				C[i][j] = C[i - 1][j - 1] + C[i - 1][j];
+		}
+	}
+
+	return C[n][k];
+}
+
+string go(int a, int b, long long k) {
+	if (k <= 0 || a <= 0 || b <= 0)
+	{
+		string ret = "";
+
+		while (a--)
+		{
+			ret += 'a';
+		}
+		while (b--)
+		{
+			ret += 'b';
+		}
+
+		return ret;
+	}
+
+	// a
+	long long c = binomialCoeff(a + b - 1, a - 1);
+	if (k <= c)
+	{
+		return 'a' + go(a - 1, b, k);
+	}
+	else
+	{
+		return 'b' + go(a, b - 1, k - c);
+	}
+}
+
+int main() {
+	long long a, b, k;
+	cin >> a >> b >> k;
+
+	cout << go(a, b, k) << endl;
+}