用Java语言写一个根据二叉树的先序和中序遍历求后序遍历

以下是Java代码实现：

public class BinaryTree {
    static int preIndex = 0;

    public static void main(String[] args) {
        int[] preOrder = {1, 2, 4, 5, 3};
        int[] inOrder = {4, 2, 5, 1, 3};

        int[] postOrder = constructTree(preOrder, inOrder, 0, inOrder.length - 1);

        System.out.print("后序遍历结果：");
        for (int i = 0; i < postOrder.length; i++) {
            System.out.print(postOrder[i] + " ");
        }
    }

    public static int[] constructTree(int[] preOrder, int[] inOrder, int inStart, int inEnd) {
        if (inStart > inEnd) {
            return null;
        }

        int rootValue = preOrder[preIndex++];
        int inIndex = search(inOrder, inStart, inEnd, rootValue);

        int[] leftTree = constructTree(preOrder, inOrder, inStart, inIndex - 1);
        int[] rightTree = constructTree(preOrder, inOrder, inIndex + 1, inEnd);

        int[] postOrder = new int[inEnd - inStart + 1];
        int postIndex = 0;

        if (leftTree != null) {
            for (int i = 0; i < leftTree.length; i++) {
                postOrder[postIndex++] = leftTree[i];
            }
        }

        if (rightTree != null) {
            for (int i = 0; i < rightTree.length; i++) {
                postOrder[postIndex++] = rightTree[i];
            }
        }

        postOrder[postIndex++] = rootValue;

        return postOrder;
    }

    public static int search(int[] inOrder, int inStart, int inEnd, int value) {
        int i;
        for (i = inStart; i <= inEnd; i++) {
            if (inOrder[i] == value) {
                return i;
            }
        }
        return i;
    }
}

输出结果：

后序遍历结果：4 5 2 3 1