先序中序建立二叉树 Java实现

package fenshujs;


import java.util.Scanner;


public class bishi {
private static class Node
{
public char s;
public Node left = null;
public Node right = null;
}
public static Node CreateTree(char[] pre,char[] in,int preleft,int preright,int inleft,int inright)
{

Node node = new Node();
node.s = pre[preleft];
if(preleft==preright)
return node;
int inroot = 0,flag = -1;
for(int i = inleft;i<=inright;i++)
{
if(in[i] == node.s)
{
inroot = i;
flag = 0;
break;
}

}
        if(-1 == flag)
        {
        return null;
        }
// inroot = pre.length - inroot - 1;
node.left = CreateTree(pre,in,preleft+1,preleft+(inroot-inleft),inleft,inroot-1);
node.right = CreateTree(pre,in,preleft+(inroot-inleft)+1 ,preright,inroot+1 ,preright);
return node;
}
public static void ShowTree(Node node)
{
if(node == null)
return;
System.out.print("[");
ShowTree(node.left);
System.out.print(node.s);
ShowTree(node.right);
System.out.print("]");
}
public static void main(String[] args){
   
Scanner sc = new Scanner(System.in);
char[] pre = sc.nextLine().toCharArray();
char[] in = sc.nextLine().toCharArray();
Node node = CreateTree(pre,in,0,pre.length-1,0,in.length-1);
ShowTree(node);



}


}