hanoi tower game

xiaoningning · xiaoningning · commit 4162c83e2e6b · 2012-07-20T00:28:00.000-07:00
diff --git a/PuzzleCoding/src/HanoiTower.java b/PuzzleCoding/src/HanoiTower.java
@@ -0,0 +1,71 @@
+import java.util.Stack;
+
+/**
+ * The discs differ in size and are initially arranged on one of the poles,
+ * in order from largest (disc n) at the bottom to smallest (disc 1) at the top.
+ * The task is to move the stack of discs to another pole, while obeying the following rules:
+ * <p/>
+ * Move only one disc at a time.
+ * Never place a disc on a smaller one.
+ * <p/>
+ * Move the top N - 1 disks from Src to Aux (using Dst as an intermediary peg)
+ * Move the bottom disk from Src to Dst
+ * Move N - 1 disks from Aux to Dst (using Src as an intermediary peg)
+ */
+public class HanoiTower {
+    public Stack<Integer> disks;
+    public int index;
+
+    public HanoiTower(int i) {
+        index = i;
+        disks = new Stack<Integer>();
+
+    }
+
+    public void addDisk(int disk) {
+        if (!disks.isEmpty()) {
+            if (disks.peek() <= disk) {
+                System.out.println("error: " + disk + " larger than " + disks.peek());
+            }
+        }
+        disks.push(disk);
+    }
+
+    public void printTower() {
+        System.out.println("tower " + index + " : " + disks.toString());
+    }
+
+    public void moveTopDisk(HanoiTower tower) {
+        if (!disks.isEmpty()) {
+            Integer disk = disks.pop();
+            tower.addDisk(disk);
+            System.out.println("move disk " + disk + " from tower " + this.index + " to tower " + tower.index);
+        } else {
+            System.out.println("tower " + index + " is empty.");
+        }
+    }
+
+    public void moveDisks(int n, HanoiTower dest, HanoiTower aux) {
+        if (n > 0) {
+            moveDisks(n - 1, aux, dest);
+            moveTopDisk(dest);
+            aux.moveDisks(n - 1, dest, this);
+        }
+    }
+
+    public static void main(String[] args) {
+        int N = 4;
+        HanoiTower[] towers = new HanoiTower[N];
+        for (int i = 1; i <= N; i++) {
+            towers[i - 1] = new HanoiTower(i);
+        }
+        for (int i = N; i > 0; i--) {
+            towers[0].addDisk(i);
+        }
+        towers[0].printTower();
+        towers[0].moveDisks(N, towers[2], towers[1]);
+        towers[2].printTower();
+
+
+    }
+}
