[익조] 20221210 "백준 - 이가 빠진 이진 트리" 풀이 제출

익조/20221210.java

@@ -0,0 +1,104 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+class Main {
+
+    static int[] nodes;
+    static StringBuilder result = new StringBuilder();
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        int n = Integer.parseInt(br.readLine()), deleteIndex = 0;
+        nodes = new int[n];
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        for (int i = 0; i < n; i++) {
+            nodes[i] = Integer.parseInt(st.nextToken());
+            if (nodes[i] == -1) {
+                deleteIndex = i;
+            }
+        }
+
+        nodes[deleteIndex] = Integer.parseInt(br.readLine());
+
+        Arrays.sort(nodes);
+
+        int mid = n / 2;
+        Node root = new Node(nodes[mid]);
+        dc(root, 0, mid - 1);
+        dc(root, mid + 1, n - 1);
+
+        postOrder(root);
+        System.out.println(result);
+    }
+
+    private static void dc(Node root, int start, int end) {
+        if (start == end) {
+            root.add(nodes[start]);
+            return;
+        }
+
+        int mid = (start + end) / 2;
+        root.add(nodes[mid]);
+        dc(root, start, mid - 1);
+        dc(root, mid + 1, end);
+    }
+
+    private static void postOrder(Node node) {
+        if (node == null) {
+            return;
+        }
+
+        postOrder(node.leftChild);
+        postOrder(node.rightChild);
+        result.append(node.value).append(" ");
+    }
+
+    private static class Node {
+        int value;
+        Node leftChild;
+        Node rightChild;
+
+        Node(int value) {
+            this.value = value;
+        }
+
+        public Node add(int value) {
+            if (this.value > value) {
+                return addLeft(value);
+            } else if (this.value < value){
+                return addRight(value);
+            } else {
+                return null;
+            }
+        }
+
+        private Node addLeft(int value) {
+            if (leftChild == null) {
+                leftChild = new Node(value);
+                return leftChild;
+            }
+
+            if (leftChild.value > value) {
+                return leftChild.addLeft(value);
+            } else {
+                return leftChild.addRight(value);
+            }
+        }
+
+        private Node addRight(int value) {
+            if (rightChild == null) {
+                rightChild = new Node(value);
+                return rightChild;
+            }
+
+            if (rightChild.value > value) {
+                return rightChild.addLeft(value);
+            } else {
+                return rightChild.addRight(value);
+            }
+        }
+    }
+}