剑指offer-问题6

package offer;

/**
 * offer interview 06
 */
public class Test06 {

    public static class BinaryTreeNode{
        int value;
        BinaryTreeNode left;
        BinaryTreeNode right;
    }

    public static BinaryTreeNode construct(int[] preorder,int[] inorder){
        if (null == preorder || null == inorder || preorder.length != inorder.length || inorder.length < 1){
            return null;
        }

        return construct(preorder,0,preorder.length-1,inorder,0,inorder.length-1);
    }

    public static BinaryTreeNode construct(int[] preorder , int ps,int pe,int[] inorder ,int is, int ie ){
        if (ps > pe){
            return null;
        }

        //root
        int value = preorder[ps];
        int index = is;

        while (index <= ie && inorder[index] != value){
            index++;
        }

        if (index > ie){
            throw new RuntimeException("Invalid input");
        }

        BinaryTreeNode node = new BinaryTreeNode();
        node.value = value;

        node.left = construct(preorder,ps+1,ps +index - is,inorder,is,index-1);
        node.right = construct(preorder,ps + index -is +1 ,pe,inorder,index + 1,ie);

        return node;
    }

    public static void printTree(BinaryTreeNode root){
        if (null != root){
            printTree(root.left);
            System.out.print(root.value + " ");
            printTree(root.right);
        }
    }

    private static void test1(){
        int[] preorder = {1,2,4,7,3,5,6,8};
        int[] inorder = {4,7,2,1,5,3,8,6};
        BinaryTreeNode root = construct(preorder,inorder);
        printTree(root);
    }

    private static void test2(){
        int[] preorder = {1,2,3,4,5};
        int[] inorder = {5,4,3,2,1};
        BinaryTreeNode root = construct(preorder,inorder);
        printTree(root);
    }

    private static void test3(){
        int[] preorder = {1,2,3,4,5};
        int[] inorder = {1,2,3,4,5};
        BinaryTreeNode root = construct(preorder,inorder);
        printTree(root);
    }


    private static void test4(){
        int[] preorder = {1};
        int[] inorder = {1};
        BinaryTreeNode root = construct(preorder,inorder);
        printTree(root);
    }

    private static void test5(){
        int[] preorder = {1,2,4,5,3,6,7};
        int[] inorder = {4,2,5,1,6,3,7};
        BinaryTreeNode root = construct(preorder,inorder);
        printTree(root);
    }

    private static void test6(){
        construct(null,null);
    }


    private static void test7(){
        int[] preorder = {1,2,4,5,3,6,7};
        int[] inorder = {4,2,8,1,6,3,7};
        BinaryTreeNode root = construct(preorder,inorder);
        printTree(root);
    }

    public static void main(String[]  args){
        test1();
        System.out.println();
        test2();
        System.out.println();
        test3();
        System.out.println();
        test4();
        System.out.println();
        test5();
        System.out.println();
        test6();
        System.out.println();
        test7();
        System.out.println();

    }



}