经典二叉树问题 根据前序和中序生成后序

转载请注明作者与出处：franciscolv http://www.cnblogs.com/franciscolv/archive/2011/11/20/2255868.html。

package SortSet;

/**
 * 根据前序和中序打印后序
 * 
 * @author Administrator
 * 
 */
public class BinarayTreeOrder {
    
    private static StringBuilder sb = new StringBuilder();
    public static void main(String[] args) {
         int[] inorder = { 1, 5, 4, 2, 3, 8, 7 };
         int[] preorder = { 2, 5, 1, 4, 8, 3, 7 };
        printPosOrder(preorder,inorder,0, 6, 0, 6);
        sb.deleteCharAt(sb.length() - 1);
        System.out.println(sb.toString());
    }

    public static void printPosOrder(int[]preorder,int[] inorder,int preleft, int preright, int inleft,
            int inright) {
        int parent, leftsize, rightsize;
        if (preleft <= preright && inleft <= inright) {
            for (parent = inleft; parent <= inright; parent++) {
                if (inorder[parent] == preorder[preleft])
                    break;
            }
            leftsize = parent - inleft;
            rightsize = inright - parent;
            if (leftsize > 0) {
                printPosOrder(preorder,inorder,preleft + 1, preleft + leftsize, inleft,
                        parent - 1);
            }
            if (rightsize > 0) {
                printPosOrder(preorder,inorder,preleft + leftsize + 1, preright, parent + 1,
                        inright);
            }
            sb.append(inorder[parent]).append(",");
        }
    }
}