Day18 2Q Jiho

Jiho/Day18/Leetcode_100. Same Tree.js

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+// p,q are roots of two binary trees
+var isSameTree = function (p, q) {
+  // 두개다 null인 경우
+  if (!p && !q) {
+    return true;
+  }
+  // 둘다 null이 아닌 경우
+  else if (!p !== null && q !== null) {
+    if (p.val !== q.val) return false;
+
+    if (
+      (p.left !== null && q.left === null) ||
+      (p.left === null && q.left !== null)
+    ) {
+      return false;
+    }
+    if (
+      (p.right !== null && q.right === null) ||
+      (p.right === null && q.right !== null)
+    ) {
+      return false;
+    }
+    return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
+  }
+  // 둘중 하나만 null인 경우
+  else {
+    return false;
+  }
+};
+
+// p,q are roots of two binary trees
+var isSameTree = function (p, q) {
+  // #1. p and q are null
+  if (!p && !q) {
+    return true;
+  }
+  // #2. p and q should not have null + same value
+  else if (!p || !q || p.val !== q.val) {
+    return false;
+  }
+  // #3. Check left and right validation
+  else {
+    // 최적화 방법
+    if (!isSameTree(p.left, q.left)) {
+      return false;
+    }
+    return isSameTree(p.right, q.right);
+    // return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
+  }
+};

Jiho/Day18/Leetcode_110. Balanced Binary Tree.js

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+// 왼쪽깊이 구하기 + 오른쪽깊이 구하기
+
+var isBalanced = function (root) {
+  if (!root) {
+    return true;
+  }
+
+  // #1. 자신
+  let l = countNodes(root.left);
+  let r = countNodes(root.right);
+
+  if (Math.abs(l - r) > 1) {
+    return false;
+  }
+  // #2. 왼쪽 오른쪽
+  return isBalanced(root.left) && isBalanced(root.right);
+};
+
+const countNodes = (root, depth = 1) => {
+  if (!root) {
+    return 0;
+  }
+
+  if (!root.left && !root.right) {
+    return depth;
+  }
+
+  return Math.max(
+    countNodes(root.left, depth + 1),
+    countNodes(root.right, depth + 1)
+  );
+};