[krokerdile] Week 06 solutions

container-with-most-water/krokerdile.js

@@ -0,0 +1,21 @@
+/**
+ * @param {number[]} height
+ * @return {number}
+ */
+var maxArea = function(height) {
+    let left = 0;
+    let right = height.length - 1;
+    let max = 0;
+
+    while(right > left){
+        if(height[left] >= height[right]){
+            max = Math.max(max, height[right] * (right - left));
+            right = right -1;
+        }
+        else{
+            max = Math.max(max, height[left] * (right - left));
+            left = left +1;
+        }
+    }
+    return max;
+};

design-add-and-search-words-data-structure/krokerdile.js

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+class TrieNode {
+    constructor() {
+      this.children = {}; // 문자 -> TrieNode 매핑
+      this.isEnd = false; // 단어의 끝 표시
+    }
+  }
+
+  class WordDictionary {
+    constructor() {
+      this.root = new TrieNode();
+    }
+
+    /**
+     * 단어를 트라이에 추가
+     * Time Complexity: O(L)  // L = word.length
+     * Space Complexity: O(L) // 새로운 노드 최대 L개 추가 가능
+     */
+    addWord(word) {
+      let node = this.root;
+      for (const char of word) {
+        if (!node.children[char]) {
+          node.children[char] = new TrieNode();
+        }
+        node = node.children[char];
+      }
+      node.isEnd = true;
+    }
+
+    /**
+     * 단어 또는 패턴 검색
+     * Time Complexity: O(26^D * L) // D = '.' 개수 (최대 2), L = word.length
+     * Space Complexity: O(L) // DFS 재귀 호출 스택 깊이
+     */
+    search(word) {
+      const dfs = (index, node) => {
+        for (let i = index; i < word.length; i++) {
+          const char = word[i];
+          if (char === '.') {
+            for (const child of Object.values(node.children)) {
+              if (dfs(i + 1, child)) return true;
+            }
+            return false;
+          } else {
+            if (!node.children[char]) return false;
+            node = node.children[char];
+          }
+        }
+        return node.isEnd;
+      };
+
+      return dfs(0, this.root);
+    }
+  }

longest-increasing-subsequence/krokerdile.js

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+// Time: O(n log n), Space: O(n)
+function lengthOfLIS(nums) {
+    const tails = [];
+
+    for (const num of nums) {
+      let left = 0, right = tails.length;
+
+      // 이진 탐색: tails에서 num이 들어갈 최소 위치 찾기
+      while (left < right) {
+        const mid = Math.floor((left + right) / 2);
+        if (tails[mid] < num) {
+          left = mid + 1;
+        } else {
+          right = mid;
+        }
+      }
+
+      // left는 삽입 위치
+      tails[left] = num;
+    }
+
+    return tails.length;
+}

spiral-matrix/krokerdile.js

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+// Time: O(m * n)
+// Space: O(1) + output array
+function spiralOrder(matrix) {
+    const result = [];
+
+    let top = 0;
+    let bottom = matrix.length - 1;
+    let left = 0;
+    let right = matrix[0].length - 1;
+
+    while (top <= bottom && left <= right) {
+      // 1. 왼 → 오
+      for (let i = left; i <= right; i++) {
+        result.push(matrix[top][i]);
+      }
+      top++;
+
+      // 2. 위 → 아래
+      for (let i = top; i <= bottom; i++) {
+        result.push(matrix[i][right]);
+      }
+      right--;
+
+      // 3. 오 → 왼
+      if (top <= bottom) {
+        for (let i = right; i >= left; i--) {
+          result.push(matrix[bottom][i]);
+        }
+        bottom--;
+      }
+
+      // 4. 아래 → 위
+      if (left <= right) {
+        for (let i = bottom; i >= top; i--) {
+          result.push(matrix[i][left]);
+        }
+        left++;
+      }
+    }
+
+    return result;
+}

valid-parentheses/krokerdile.js

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+/**
+ * @param {string} s
+ * @return {boolean}
+ */
+var isValid = function(s) {
+    let ch = {};
+    ch[')'] = '(';
+    ch['}'] = '{';
+    ch[']'] = '[';
+
+    let list = s.split('');
+    let stack = [];
+
+    list.forEach((ele)=>{
+        if(stack.length == 0){
+            stack.push(ele);
+        }else{
+            let len = stack.length;
+            if(stack[len-1] == ch[ele]){
+                stack.pop();
+            }else{
+                stack.push(ele);
+            }
+        }
+    })
+    if(stack.length == 0){
+        return true;
+    }else{
+        return false;
+    }
+};