Google Code Jam 2015, round 0.

puzzles/google_code_jam/2015/0-C.cpp

@@ -0,0 +1,139 @@
+/*
+VIM: let g:lcppflags="-std=c++11 -O2 -pthread"
+VIM: let g:wcppflags="/O2 /EHsc /DWIN32"
+*/
+
+#include <assert.h>
+#include <iostream>
+#include <sstream>
+#include <fstream>
+#include <iomanip>
+#include <exception>
+#include <stdexcept>
+#include <map>
+#include <set>
+#include <list>
+#include <vector>
+#include <string>
+#include <memory>
+#include <functional>
+#include <algorithm>
+#include <utility>
+#include <limits> 
+#include <math.h>
+
+typedef long long ll;
+typedef std::vector<ll> vec;
+
+/*
+Read n values into v
+*/
+template <class V>
+void readv(V& v, int n)
+{
+	v.reserve(n);
+	for (int i = 0; i < n; ++i)
+	{
+		typename V::value_type e;
+		std::cin >> e;
+		assert(!std::cin.fail());
+		v.push_back(e);
+	}
+}
+
+/*
+Problem
+*/
+
+int mul(int a, int b)
+{
+	static int m[4][4] = {
+		{ 1, 2, 3, 4 },
+		{ 2,-1, 4,-3 },
+		{ 3,-4,-1, 2 },
+		{ 4, 3,-2,-1 }
+	};
+	int r = 1;
+	if (a < 0)
+	{
+		r *= -1;
+		a = -a;
+	}
+	if (b < 0)
+	{
+		r *= -1;
+		b = -b;
+	}
+	r *= m[a-1][b-1];
+	return r;
+}
+
+std::string yesno(bool b)
+{
+	return b ? std::string("YES") : std::string("NO");
+}
+
+std::string solve_puzzle()
+{
+	ll l, x;
+	std::string s;
+	std::cin >> l >> x >> s;
+
+	int m = 1;
+	int n = 1;
+	bool I = false;
+	bool J = false;
+	for (int i = 0; i < x && i < 12; ++i) {
+		for (auto c : s) {
+			m = mul(m, c - 'g');
+			if (!I && m == 2)
+				I = true;
+			else if (I && !J && m == 4)
+				J = true;
+		}
+		if (i == 0)
+			n = m;
+	}
+	assert(x < 4 || m == 1 || I && J);
+	//std::cout << n << ' ';
+
+	if (n == 1)
+		return yesno(false);
+	else if (n == -1 && x % 2 != 1)
+		return yesno(false);
+	else if (n != -1 && x % 4 != 2)
+		return yesno(false);
+	else
+		return yesno(I && J);
+}
+
+int main(void)
+{
+	try{
+		srand((unsigned)time(NULL));
+		int puzzle_count;
+
+		std::cin >> puzzle_count;
+		std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
+		for (int i = 1; i <= puzzle_count; i++)
+		{
+			std::cout << "Case #" << i << ": ";
+			auto r = solve_puzzle();
+			std::cout << r << std::endl;
+		}
+
+		return 0;
+	}
+	catch (const std::exception& e)
+	{
+		std::cerr << std::endl
+			<< "std::exception(\"" << e.what() << "\")." << std::endl;
+		return 2;
+	}
+	catch (...)
+	{
+		std::cerr << std::endl
+			<< "unknown exception." << std::endl;
+		return 1;
+	}
+}