二叉树中两个节点的最低公共祖节点

Posted 2020-12-23 放下也不自在

/**
 * 二叉树中两个节点的最低公共祖节点
 */
public class LowerAncestors {

    public static Node lowerAncestors(Node head, Node o1, Node o2) {
        return process(head, o1, o2).result;
    }

    private static ResultInfo process(Node node, Node o1, Node o2) {
        if (node == null) {
            return new ResultInfo(null, false, false);
        }
        ResultInfo leftInfo = process(node.left, o1, o2);
        ResultInfo rightInfo = process(node.right, o1, o2);

        boolean findO1 = node == o1 || leftInfo.findO1 || rightInfo.findO1;
        boolean findO2 = node == o2 || leftInfo.findO2 || rightInfo.findO2;
        Node result = leftInfo.result != null ? leftInfo.result : rightInfo.result != null ? rightInfo.result : null;
        result = result == null && findO1 && findO2 ? node : result;
        return new ResultInfo(result, findO1, findO2);
    }

    public static class ResultInfo {

        public Node result;

        public boolean findO1;

        public boolean findO2;

        public ResultInfo(Node node, boolean b1, boolean b2) {
            result = node;
            findO1 = b1;
            findO2 = b2;
        }

    }

    public static class Node {

        public int value;

        public Node left;

        public Node right;

        public Node(int data) {
            this.value = data;
        }

    }

}

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