Merge pull request #81 from solid-connection/Hexeong

[Week13] PGS 42892: 길 찾기 게임

Author: Hexeong

weekly/week13/PGS_ 42892_길찾기게임/Hexeong.java

@@ -0,0 +1,70 @@
+import java.util.*;
+
+class Solution {
+    int[][] answer;
+    int idx;
+
+    public int[][] solution(int[][] nodeinfo) {
+        int n = nodeinfo.length;
+        List<Node> nodes = new ArrayList<>();
+        
+        for (int i = 0; i < n; i++) {
+            nodes.add(new Node(i + 1, nodeinfo[i][0], nodeinfo[i][1]));
+        }
+
+        nodes.sort((a, b) -> {
+            if (a.y == b.y) return a.x - b.x;
+            return b.y - a.y;
+        });
+
+        Node root = nodes.get(0);
+        for (int i = 1; i < nodes.size(); i++) {
+            insertNode(root, nodes.get(i));
+        }
+
+        answer = new int[2][n];
+        idx = 0;
+        preOrder(root);
+        idx = 0;
+        postOrder(root);
+
+        return answer;
+    }
+
+    private void insertNode(Node parent, Node child) {
+        if (child.x < parent.x) {
+            if (parent.left == null) parent.left = child;
+            else insertNode(parent.left, child);
+        } else {
+            if (parent.right == null) parent.right = child;
+            else insertNode(parent.right, child);
+        }
+    }
+
+    // 전위 순회
+    private void preOrder(Node node) {
+        if (node == null) return;
+        answer[0][idx++] = node.id;
+        preOrder(node.left);
+        preOrder(node.right);
+    }
+
+    // 후위 순회
+    private void postOrder(Node node) {
+        if (node == null) return;
+        postOrder(node.left);
+        postOrder(node.right);
+        answer[1][idx++] = node.id;
+    }
+
+    class Node {
+        int id, x, y;
+        Node left, right;
+
+        public Node(int id, int x, int y) {
+            this.id = id;
+            this.x = x;
+            this.y = y;
+        }
+    }
+}