leetcode stack

Author: geekidentity

.gitignore

@@ -0,0 +1,30 @@
+target/
+!.mvn/wrapper/maven-wrapper.jar
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+### NetBeans ###
+nbproject/private/
+build/
+nbbuild/
+dist/
+nbdist/
+.nb-gradle/
+
+###
+
+elasticsearch.keystore
+
+logs

pom.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.example</groupId>
+    <artifactId>LeetCode-Java</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <properties>
+        <maven.compiler.source>17</maven.compiler.source>
+        <maven.compiler.target>17</maven.compiler.target>
+    </properties>
+
+</project>

src/main/java/com/geekidentity/leetcode/offer/stack/CQueue.java

@@ -0,0 +1,32 @@
+package com.geekidentity.leetcode.offer.stack;
+
+import java.util.Stack;
+
+/**
+ * 剑指 Offer 30. 包含min函数的栈
+ * https://leetcode-cn.com/problems/bao-han-minhan-shu-de-zhan-lcof/
+ */
+public class CQueue {
+    private final Stack<Integer> inStack = new Stack<>();
+    private final Stack<Integer> outStack = new Stack<>();
+
+    public CQueue() {
+
+    }
+
+    public void appendTail(int value) {
+        inStack.push(value);
+    }
+
+    public int deleteHead() {
+        if (outStack.isEmpty()) {
+            while (!inStack.isEmpty()) {
+                outStack.push(inStack.pop());
+            }
+        }
+        if (outStack.isEmpty()) {
+            return -1;
+        }
+        return outStack.pop();
+    }
+}

src/main/java/com/geekidentity/leetcode/offer/stack/MinStack.java

@@ -0,0 +1,64 @@
+package com.geekidentity.leetcode.offer.stack;
+
+import java.util.Stack;
+
+/**
+ * 剑指 Offer 30. 包含min函数的栈
+ * https://leetcode-cn.com/problems/bao-han-minhan-shu-de-zhan-lcof/
+ */
+public class MinStack {
+
+    private final Stack<Integer> stack = new Stack<>();
+    private final Stack<Integer> minStack = new Stack<>();
+
+
+    public MinStack() {
+
+    }
+
+    public void push(int x) {
+        stack.push(x);
+        if (!minStack.isEmpty()) {
+            int min = minStack.peek();
+            if (x < min) {
+                min = x;
+            }
+            minStack.push(min);
+        } else {
+            minStack.push(x);
+        }
+    }
+
+    public void pop() {
+        if (!minStack.isEmpty()) {
+            minStack.pop();
+            stack.pop();
+        }
+
+    }
+
+    public int top() {
+        if (minStack.isEmpty()) {
+            return -1;
+        }
+        return stack.peek();
+    }
+
+    public int min() {
+        if (minStack.isEmpty()) {
+            return -1;
+        }
+        return minStack.peek();
+    }
+
+    public static void main(String[] args) {
+        MinStack stack = new MinStack();
+        stack.push(1);
+        stack.push(2);
+        System.out.println(stack.top());
+        System.out.println(stack.min());
+        stack.pop();
+        System.out.println(stack.min());
+        System.out.println(stack.top());
+    }
+}