import lombok.*;

/**
 * @author: Small sunshine
 * @Description：
 * @date: 2021/6/30 8:05 下午
 */
public class SortTree {

    public static void main(String[] args) {
        Tree treeG = new Tree('G', null, null);
        Tree treeD = new Tree('D', null, null);
        Tree treeF = new Tree('F', null, null);
        Tree treeE = new Tree('E', treeF, null);
        Tree treeB = new Tree('B', treeD, treeE);
        Tree treeC = new Tree('C', treeG, null);
        Tree treeA = new Tree('A', treeB, treeC);
        //前序排列
        System.out.print("前序排列：");
        VLR(treeA);
        System.out.println();
        //中序排列
        System.out.print("中序排列：");
        LDR(treeA);
        System.out.println();
        //後序排列
        System.out.print("後序排列：");
        LRD(treeA);
        System.out.println();


    }

    /**
     * 輸出節點
     *
     * @param tree
     */
    public static void print(Tree tree) {
        System.out.print(tree.getData());
    }

    /**
     * 前序排列-VLR
     *
     * @param tree
     */
    public static void VLR(Tree tree) {
        print(tree);
        if (tree.left != null) {
            VLR(tree.left);
        }
        if (tree.right != null) {
            VLR(tree.right);
        }
    }

    /**
     * 中序排序-LDR
     *
     * @param tree
     */
    public static void LDR(Tree tree) {
        if (tree.left != null) {
            LDR(tree.left);
        }
        print(tree);
        if (tree.right != null) {
            LDR(tree.right);
        }
    }

    /**
     * 後序排列-LRD
     *
     * @param tree
     */
    public static void LRD(Tree tree) {
        if (tree.left != null) {
            LRD(tree.left);
        }
        if (tree.right != null) {
            LRD(tree.right);
        }
        print(tree);
    }


    @Data
    @ToString
    @AllArgsConstructor
    @NoArgsConstructor
    public static class Tree {
        private char data;
        private Tree left;
        private Tree right;
    }
}