max stack with std::pair

rudi8848 · rudi8848 · commit 507b5ca9d250 · 2019-01-24T14:00:03.000+02:00
diff --git a/1/stack_max1.cpp b/1/stack_max1.cpp
@@ -0,0 +1,68 @@
+#include <iostream>
+#include <stack>
+#include <vector>
+#include <utility>
+
+/*	std::pair(val, max)*/
+struct MaxStack
+{
+	void	pushv(int val) {
+		_st.empty() ? _st.push(std::make_pair(val, val))
+		: _st.push(std::make_pair(val, std::max(val, _st.top().second)));
+	}
+
+	void	popv() {
+		if (!_st.empty())
+			_st.pop();
+	}
+
+	int		max() {
+		if (!_st.empty())
+			return _st.top().second;
+		else
+			return -1;
+	}
+
+private:
+	std::stack <std::pair<int, int>>	_st;
+};
+
+void	read_commands(int n)
+{
+	std::string command;
+	int val;
+	MaxStack st;
+	int ret;
+
+	std::vector<int> log;
+	while (n != 0)
+	{
+		std::cin >> command;
+		if (command == "max")
+		{
+			ret = st.max();
+			if (ret >= 0)
+				log.push_back(ret);
+		}
+		else if (command == "pop")
+				st.popv();
+		else if (command == "push")
+		{
+			std::cin >> val;
+				st.pushv(val);
+		}
+		--n;
+	}
+	for (int i = 0; i < log.size(); ++i)
+		std::cout << log[i] << std::endl;
+}
+
+int		main(void)
+{
+	int n = 0;
+	std::cin >> n;
+
+	if (n)
+		read_commands(n);
+	return 0;
+}
