Merge pull request #479 from whewchews/main

[pepper] Week 6 Solutions

container-with-most-water/whewchews.ts

@@ -0,0 +1,24 @@
+function maxArea(height: number[]): number {
+ let left = 0;
+ let right = height.length - 1;
+ let maxSize = 0;
+
+ while (left < right) {
+ maxSize = Math.max(maxSize, getMaxSize(height, left, right));
+
+ if (height[left] < height[right]) {
+ left++;
+ } else {
+ right--;
+ }
+ }
+
+ return maxSize;
+}
+
+function getMaxSize(height: number[], left: number, right: number) {
+ return Math.min(...[height[right], height[left]]) * (right - left);
+}
+
+// TC: O(n)
+// SC: O(1)

design-add-and-search-words-data-structure/whewchews.ts

@@ -0,0 +1,48 @@
+class WordDictionary {
+ wordCountMap: Map<number, Set<string>>;
+ constructor() {
+ this.wordCountMap = new Map();
+ }
+
+ // TC: O(1)
+ // SC: O(n)
+ addWord(word: string): void {
+ const length = word.length;
+ if (this.wordCountMap.has(length)) {
+ this.wordCountMap.get(length).add(word);
+ } else {
+ this.wordCountMap.set(length, new Set([word]));
+ }
+ return null;
+ }
+
+ // TC: O(m*n) // m: words length, n: word length
+ // SC: O(n)
+ search(word: string): boolean {
+ const len = word.length;
+ const targetWord = word.replace(/\./g, "");
+ const hasDot = len - targetWord.length !== 0;
+
+ if (!this.wordCountMap.has(len)) {
+ return false;
+ }
+ const words = this.wordCountMap.get(len);
+ if (!hasDot) {
+ return words.has(word);
+ }
+
+ for (const w of words) {
+ let match = true;
+ for (let j = 0; j < w.length; j++) {
+ if (word[j] !== "." && word[j] !== w[j]) {
+ match = false;
+ break;
+ }
+ }
+ if (match) {
+ return true;
+ }
+ }
+ return false;
+ }
+}

spiral-matrix/whewchews.ts

@@ -0,0 +1,39 @@
+function spiralOrder(matrix: number[][]): number[] {
+ const rows = matrix.length;
+ const cols = matrix[0].length;
+ const total = rows * cols;
+ let srow = 0; // start row
+ let scol = 0;
+ let erow = rows - 1; // end row
+ let ecol = cols - 1;
+ let count = 0;
+ const ans: number[] = [];
+
+ while (count < total) {
+ for (let i = scol; i <= ecol && count < total; i++) {
+ ans.push(matrix[srow][i]);
+ count++;
+ }
+ srow++;
+ for (let i = srow; i <= erow && count < total; i++) {
+ ans.push(matrix[i][ecol]);
+ count++;
+ }
+ ecol--;
+ for (let i = ecol; i >= scol && count < total; i--) {
+ ans.push(matrix[erow][i]);
+ count++;
+ }
+ erow--;
+ for (let i = erow; i >= srow && count < total; i--) {
+ ans.push(matrix[i][scol]);
+ count++;
+ }
+ scol++;
+ }
+
+ return ans;
+}
+
+// TC: O(m*n)
+// SC: O(m*n)

valid-parentheses/whewchews.ts

@@ -0,0 +1,35 @@
+/*
+ * 아이디어
+ * stack 자료구조를 사용해 여는 괄호가 나오면 순서대로 저장해둔다.
+ * stack을 사용하는 이유는 가장 최근 여는 괄호가 어떤 것인지 확인하기 위함이다.(마지막에 삽입한 값을 먼저 사용함)
+ * 닫는 괄호가 나오면 stack의 마지막 값이 pair인 여는 괄호인지 체크한다. 다르면 return false
+ * 문자열 반복문을 다 돌고 stack에 여는 괄호가 남아있지 않은지 본다. 남아있으면 return false
+ * 위의 두 경우에 해당되지 않으면 return true
+ */
+function isValid(s: string): boolean {
+ const openCharStack = [];
+ const CHAR_PAIR = {
+ "]": "[",
+ "}": "{",
+ ")": "(",
+ };
+
+ for (let i = 0; i <= s.length - 1; i++) {
+ const char = s[i];
+
+ if (char in CHAR_PAIR) {
+ const pair = CHAR_PAIR[char];
+ const lastOpenChar = openCharStack.pop();
+ if (lastOpenChar !== pair) {
+ return false;
+ }
+ } else {
+ openCharStack.push(char);
+ }
+ }
+
+ const isEmpty = openCharStack.length === 0;
+ return isEmpty;
+}
+// TC: O(n)
+// SC: O(n)