#4 add HanMoTa problem

src/main/java/dp/HanMoTa.java

@@ -0,0 +1,59 @@
+package dp;
+
+/**
+ * Created by tianliangxia on 16-10-23.
+ */
+
+/***
+ * 汗莫塔问题
+ * 给定三个柱子  src mid des
+ * 输出将n个圆盘从src移动到des上的路径
+ */
+
+class StackElement{
+    public String src, mid, des;
+    public int n;
+    public StackElement(int n, String src, String mid, String des){
+        this.n = n;
+        this.src = src;
+        this.mid = mid;
+        this.des = des;
+    }
+}
+
+public class HanMoTa {
+    public static void solve(int n, StringBuilder stringBuilder, String src, String mid, String des){
+        if(stringBuilder == null)
+            throw new NullPointerException("stringBuilder is null");
+        if(n == 1){
+            stringBuilder.append(src+"->"+des+",");
+            return;
+        }
+
+        solve(n-1, stringBuilder, src, des, mid);
+        stringBuilder.append(src+"->"+des+",");
+        solve(n-1, stringBuilder,mid, src, des);
+    }
+
+    public static void solveWithStack(int n, StringBuilder stringBuilder, String src, String mid, String des){
+        if(stringBuilder == null)
+            throw new NullPointerException("stringBuilder is null");
+
+        MyStack<StackElement> stack = new MyStack<>();
+        stack.push(new StackElement(n, src, mid, des));
+        StackElement element;
+        while (!stack.isEmpty()){
+            element = stack.pop();
+            if(element.n == 1){
+                stringBuilder.append(element.src+"->"+element.des+",");
+            }else {
+                stack.push(new StackElement(element.n-1, element.mid, element.src, element.des));
+                stack.push(new StackElement(1, element.src, element.mid, element.des));
+                //stringBuilder.append(element.src+"->"+element.des+",");   递归时上面返回才会执行这一步  stack会直接执行
+                stack.push(new StackElement(element.n-1, element.src, element.des, element.mid));
+            }
+        }
+    }
+
+
+}

src/main/java/dp/MyStack.java

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+package dp;
+
+
+import java.util.LinkedList;
+
+/**
+ * Created by tianliangxia on 16-10-23.
+ */
+public class MyStack<T> extends LinkedList<T> implements  MyStackInterface<T>{
+    public MyStack(){
+        super();
+    }
+    public void push(T t){
+        addLast(t);
+    }
+    public T top(){
+        return getLast();
+    }
+    public T pop(){
+        return removeLast();
+    }
+    public int size(){
+        return super.size();
+    }
+    public boolean isEmpty(){
+        return super.isEmpty();
+    }
+}

src/main/java/dp/MyStackInterface.java

@@ -0,0 +1,12 @@
+package dp;
+
+/**
+ * Created by tianliangxia on 16-10-23.
+ */
+public interface MyStackInterface<T> {
+    void push(T t);
+    T top();
+    T pop();
+    int size();
+    boolean isEmpty();
+}

src/test/java/dp/HanMoTaTest.java

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+package dp;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+/**
+ * Created by tianliangxia on 16-10-23.
+ */
+public class HanMoTaTest {
+
+    @Test
+    public void test(){
+        String res = "src->des,";
+        StringBuilder stringBuilder = new StringBuilder();
+        HanMoTa.solve(1, stringBuilder, "src", "mid", "des");
+        assertEquals(res, stringBuilder.toString());
+
+        res = "src->mid,src->des,mid->des,";
+        stringBuilder = new StringBuilder();
+        HanMoTa.solve(2, stringBuilder, "src", "mid", "des");
+        assertEquals(res, stringBuilder.toString());
+    }
+
+    @Test
+    public void test2(){
+        StringBuilder stringBuilder1 = new StringBuilder();
+        StringBuilder stringBuilder2 = new StringBuilder();
+        int n = 10;
+        HanMoTa.solve(n, stringBuilder1, "src","mid","des");
+        //System.out.println(stringBuilder1.toString());
+        HanMoTa.solveWithStack(n, stringBuilder2, "src","mid","des");
+        assertEquals(stringBuilder1.toString(), stringBuilder2.toString());
+    }
+
+}