[20251007] PGM / Lv3 / 표현 가능한 이진 트리 / 이강현

lkhyun/202510/07 PGM Lv3 표현 가능한 이진 트리.md

@@ -0,0 +1,47 @@
+```java
+class Solution {
+    public int[] solution(long[] numbers) {
+        int[] answer = new int[numbers.length];
+
+        for(int i = 0; i < numbers.length; i++){
+            answer[i] = isPossible(numbers[i]) ? 1 : 0;
+        }
+
+        return answer;
+    }
+
+    public boolean isPossible(long number){
+        String binary = Long.toBinaryString(number);
+
+        int height = 1;
+        while ((1 << height) - 1 < binary.length()) {
+            height++;
+        }
+        int treeSize = (1 << height) - 1;
+
+        StringBuilder sb = new StringBuilder();
+        for(int i = 0; i < treeSize - binary.length(); i++){
+            sb.append('0');
+        }
+        sb.append(binary);
+
+        return isValidTree(sb.toString(), 0, treeSize - 1);
+    }
+
+    private boolean isValidTree(String tree, int start, int end){
+        if(start > end) return true;
+
+        int mid = (start + end) / 2;
+        char root = tree.charAt(mid);
+
+        if(root == '0'){
+            for(int i = start; i <= end; i++){
+                if(tree.charAt(i) == '1') return false;
+            }
+        }
+
+        return isValidTree(tree, start, mid - 1) && 
+               isValidTree(tree, mid + 1, end);
+    }
+}
+```