加入算法第四版本依赖的jar包

.gitignore

@@ -5,7 +5,7 @@
 *.so
 *.dylib
 *.DS_Store
-
+algorithms4th/out/
 # Test binary, built with `go test -c`
 *.test
 

algorithms4th/REAEME.md

@@ -0,0 +1,12 @@
+# 算法第 4 版本
+
+是时候来学习这门课程了
+
+项目依赖的 jar 包在 [deplib](deplib) 文件夹下
+
+
+辅助配套学习资料 
+
+1. [可视化算法资料](https://visualgo.net/en/bitmask)
+2. [配套学习网站](https://introcs.cs.princeton.edu/java/stdlib/)
+

algorithms4th/algorithms4th.iml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="library" name="algs4" level="project" />
+    <orderEntry type="module-library">
+      <library>
+        <CLASSES>
+          <root url="jar://$MAVEN_REPOSITORY$/org/jetbrains/annotations/20.1.0/annotations-20.1.0.jar!/" />
+        </CLASSES>
+        <JAVADOC />
+        <SOURCES />
+      </library>
+    </orderEntry>
+  </component>
+</module>

algorithms4th/src/com/xx/GCD.java

@@ -0,0 +1,40 @@
+/**
+ * 求两个数的最大公约数
+ */
+package com.xx;
+
+import edu.princeton.cs.algs4.StdOut;
+
+public class GCD {
+    /**
+     * @param a 输入 数 a
+     * @param b 输入 b
+     * @return
+     * @desc 计算 两个数的最大公约数
+     */
+    public static int gcd(int a, int b) {
+        int temp = 0;
+        if (a > b) {
+            temp = a;
+            a = b;
+            b = temp;
+        }
+        // 如果其中一个为 0，直接返回 0
+        if (a == 0 || b == 0) {
+            return 0;
+        }
+        while (b > 0) {
+            temp = a % b; // a % b  等价于 a - (a/b)*b
+            a = b;
+            b = temp;
+        }
+        return a;
+    }
+
+    public static void main(String[] args) {
+        StdOut.println(gcd(24, 3));
+        StdOut.println(gcd(24, 6));
+        StdOut.println(gcd(24, 1));
+        StdOut.println(gcd(24, 0));
+    }
+}

algorithms4th/src/com/xx/Main.java

@@ -0,0 +1,31 @@
+package com.xx;
+
+import edu.princeton.cs.algs4.StdOut;
+
+public class Main {
+    public static int gcd(int m, int n) {
+        int rem;
+        while (n > 0) {
+            rem = m % n;
+            m = n;
+            n = rem;
+        }
+        return m;
+    }
+
+    public static void main(String[] args) {
+        System.out.println("study algorithms 4th code");
+        StdOut.println(StdOut.class.toString());
+        System.out.println(System.class.toString()); // 输出类名
+        System.out.println(gcd(24, 4));
+        System.out.println(gcd(24, 1));
+        System.out.println(gcd(24, 2));
+        System.out.println(gcd(24, 3));
+        System.out.println(Main.isMain);
+
+    }
+
+    final static int a = 1;
+    static final int b = 2;
+    final static public boolean isMain = true && ((a ^ b ) == 0) ;
+}

algorithms4th/src/com/xx/character1/Evaluate.java

@@ -0,0 +1,48 @@
+package com.xx.character1;
+
+import edu.princeton.cs.algs4.StdIn;
+import edu.princeton.cs.algs4.StdOut;
+
+import java.util.Stack;
+
+public class Evaluate {
+    public static void main(String[] args) {
+        Stack<String> ops = new Stack<String>(); // 操作符号
+        Stack<Double> vals = new Stack<Double>(); // 操作数
+
+        while (!StdIn.isEmpty()) {
+            String s = StdIn.readString();
+            if (s.equals("(")) {
+                ;
+            } else if (s.equals("+")) {
+                ops.push(s);
+            } else if (s.equals("-")) {
+                ops.push(s);
+            } else if (s.equals("*")) {
+                ops.push(s);
+            } else if (s.equals("/")) {
+                ops.push(s);
+            } else if (s.equals("sqrt")) {
+                ops.push(s);
+            } else if (s.equals(")")) { // 获取的是右括号
+                String op = ops.pop();  // 获取操作符号
+                double v = vals.pop();  // 获取操作数
+                if (op.equals("+")) {   // 如果操作符号是 +
+                    v = vals.pop() + v; // 再弹一个栈并且相加
+                } else if (op.equals("-")) { //  如果当前的操作符号是 -
+                    v = vals.pop() - v; // 再弹出一个操作数并且相减
+                } else if (op.equals("*")) {
+                    v = vals.pop() * v;
+                } else if (op.equals("/")) {
+                    v = vals.pop() / v;
+                } else {
+                    v = Math.sqrt(v);
+                }
+                vals.push(v);
+            } else {
+                vals.push(Double.parseDouble(s));
+            }
+        }
+        StdOut.println(vals.pop());
+    }
+}

algorithms4th/src/com/xx/character1/Parenthsses.java

@@ -0,0 +1,54 @@
+package com.xx.character1;
+
+import com.xx.mycontainer.Stack;
+
+public class Parenthsses {
+    public static void main(String[] args) {
+        System.out.println(isOk("{ ]"));
+        System.out.println(isOk("{ }"));
+        System.out.println(isOk("{ {"));
+        System.out.println(isOk("{ { } )"));
+        System.out.println(isOk(""));
+    }
+
+    public static boolean isOk(String data) {
+        String[] sp = data.split(" ");
+        Stack<String> ss = new Stack<>();
+        String tmp;
+        for (String s : sp) {
+            if (s.equals(")")) {
+                tmp = ss.pop();
+                if (tmp == null) {
+                    return false;
+                }
+                if (!tmp.equals("(")) {
+                    return false;
+                }
+            } else if (s.equals("]")) {
+                tmp = ss.pop();
+                if (tmp == null) {
+                    return false;
+                }
+                if (!tmp.equals("[")) {
+                    return false;
+                }
+            } else if (s.equals("}")) {
+                tmp = ss.pop();
+                if (tmp == null) {
+                    return false;
+                }
+                if (!tmp.equals("{")) {
+                    return false;
+                }
+            } else {
+                ss.push(s);
+            }
+        }
+        return ss.isEmpty();
+    }
+
+    private class Item {
+        private String data /* "{[)}"*/;
+        private boolean isOk;
+    }
+}

algorithms4th/src/com/xx/character1/Stack.java

@@ -0,0 +1,89 @@
+package com.xx.character1;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Iterator;
+import java.util.Spliterator;
+import java.util.function.Consumer;
+
+public class Stack<Item> implements Iterable<Item> {
+    public static void main(String[] args) {
+        Stack<Integer> is = new Stack<>();
+        is.push(23);
+        is.push(3);
+        is.push(1);
+        for (Integer i : is) {
+            System.out.println(i.toString());
+        }
+    }
+
+    private class Node {
+        Item item;
+        Node next;
+    }
+
+    private Node first;
+    private int N;
+
+    public boolean isEmpty() {
+        return first == null;
+    }
+
+    public int size() {
+        return this.N;
+    }
+
+    public void push(Item item) {
+        Node oldFirst = first;
+        first = new Node();
+        first.item = item;
+        first.next = oldFirst;
+        this.N++;
+    }
+
+    public Item pop() {
+        Item item = first.item;
+        first = first.next;
+        this.N--;
+        return item;
+
+    }
+
+
+    @NotNull
+    @Override
+    public Iterator<Item> iterator() {
+        return new ListIterator();
+    }
+
+    @Override
+    public void forEach(Consumer<? super Item> action) {
+
+    }
+
+    @Override
+    public Spliterator<Item> spliterator() {
+        return null;
+    }
+
+    private class ListIterator implements Iterator<Item> {
+        private Node current = first;
+
+        @Override
+        public boolean hasNext() {
+            return current != null;
+        }
+
+        @Override
+        public Item next() {
+            Item item = current.item;
+            current = current.next;
+            return item;
+        }
+
+        @Override
+        public void remove() {
+
+        }
+    }
+}

algorithms4th/src/com/xx/character2/Example.java

@@ -0,0 +1,48 @@
+/*
+ java 中的排序模板
+ */
+
+package com.xx.character2;
+
+public class Example {
+
+    // 排序函数
+    public static void sort(Comparable[] a) {
+        // todo
+    }
+
+    // 判断是否小于
+    private static boolean less(Comparable v, Comparable w) {
+        return v.compareTo(w) < 0;
+    }
+
+    // 交换待比较中的元素
+    private static void exch(Comparable[] a, int i, int j) {
+        Comparable tem = a[i];
+        a[i] = a[j];
+        a[j] = tem;
+    }
+
+    // 打印数组
+    private static void show(Comparable[] a) {
+        for (Comparable ca : a) {
+            System.out.print(ca);
+        }
+        System.out.println();
+    }
+
+    /**
+     * 判断是否已经有序
+     *
+     * @param a 入参
+     * @return true 有序, false 无序
+     */
+    public static boolean isSorted(Comparable[] a) {
+        for (int i = 1; i < a.length; i++) {
+            if (less(a[i], a[i - 1])) {
+                return false;
+            }
+        }
+        return true;
+    }
+}