Solve LeetCode 75 problems 01-12

Author: THammami01

LeetCode-75/.vscode/launch.json

@@ -0,0 +1,17 @@
+{
+  // Use IntelliSense to learn about possible attributes.
+  // Hover to view descriptions of existing attributes.
+  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    // {
+    //   "type": "node",
+    //   "request": "launch",
+    //   "name": "Launch Program",
+    //   "skipFiles": [
+    //     "<node_internals>/**"
+    //   ],
+    //   "program": "${workspaceFolder}\\LeetCode-75\\11.js"
+    // }
+  ]
+}

LeetCode-75/01-1768.ts

@@ -0,0 +1,24 @@
+// https://leetcode.com/problems/greatest-common-divisor-of-strings/description/?envType=study-plan-v2&envId=leetcode-75
+
+const isStrValid = (str: string, substrLen: number): boolean => {
+  const substrToCheck = str.substring(0, substrLen);
+  return !str.split(substrToCheck).filter((val) => !!val).length;
+};
+
+const gcdOfStrings = (str1: string, str2: string): string => {
+  const maxStrLen = str1.length < str2.length ? str1.length : str2.length;
+  let substrLen = maxStrLen;
+
+  while (substrLen > 0) {
+    if (
+      isStrValid(str1, substrLen) &&
+      isStrValid(str2, substrLen) &&
+      str1.startsWith(str2.substring(0, substrLen))
+    )
+      return str1.substring(0, substrLen);
+
+    substrLen--;
+  }
+
+  return "";
+};

LeetCode-75/02-1071.ts

@@ -0,0 +1,17 @@
+// https://leetcode.com/problems/merge-strings-alternately/?envType=study-plan-v2&envId=leetcode-75
+
+const mergeAlternately = (word1: string, word2: string): string => {
+  const minLen = word1.length < word2.length ? word1.length : word2.length;
+
+  const word2Chars = word2.substring(0, minLen).split("");
+
+  return (
+    word1
+      .substring(0, minLen)
+      .split("")
+      .map((char, idx) => char + word2Chars[idx])
+      .join("") +
+    word1.substring(minLen) +
+    word2.substring(minLen)
+  );
+};

LeetCode-75/03-1431.ts

@@ -0,0 +1,13 @@
+// https://leetcode.com/problems/kids-with-the-greatest-number-of-candies/?envType=study-plan-v2&envId=leetcode-75
+
+const kidsWithCandies = (
+  candies: number[],
+  extraCandies: number
+): boolean[] => {
+  const biggestCandiesCountOwned = candies.reduce(
+    (acc, val) => (val > acc ? val : acc),
+    0
+  );
+
+  return candies.map((el) => el + extraCandies >= biggestCandiesCountOwned);
+};

LeetCode-75/04-605.ts

@@ -0,0 +1,22 @@
+// https://leetcode.com/problems/can-place-flowers/description/?envType=study-plan-v2&envId=leetcode-75
+
+const canPlaceFlowers = (flowerbed: number[], n: number): boolean => {
+  let remaining = n,
+    idx = 0;
+
+  while (remaining && idx < flowerbed.length) {
+    if (
+      !flowerbed[idx] &&
+      ((idx === 0 && !flowerbed[idx + 1]) ||
+        (idx === flowerbed.length - 1 && !flowerbed[idx - 1]) ||
+        (!flowerbed[idx - 1] && !flowerbed[idx + 1]))
+    ) {
+      flowerbed[idx] = 1;
+      remaining--;
+    }
+
+    idx++;
+  }
+
+  return !remaining;
+};

LeetCode-75/05-345.ts

@@ -0,0 +1,23 @@
+// https://leetcode.com/problems/reverse-vowels-of-a-string/?envType=study-plan-v2&envId=leetcode-75
+
+const VOWELS = ["a", "e", "i", "o", "u"];
+
+const reverseVowels = (str: string): string => {
+  const savedVowels: string[] = [];
+  const savedIdxs: number[] = [];
+  const newStrArr = str.split("");
+  str = str.toLowerCase();
+
+  for (let i = 0; i <= str.length; i++)
+    if (VOWELS.includes(str[i])) {
+      savedIdxs.push(i);
+      savedVowels.push(newStrArr[i]);
+    }
+
+  savedIdxs.forEach(
+    (vowelIdx, idx) =>
+      (newStrArr[vowelIdx] = savedVowels[savedIdxs.length - idx - 1])
+  );
+
+  return newStrArr.join("");
+};

LeetCode-75/06-151.ts

@@ -0,0 +1,7 @@
+// https://leetcode.com/problems/reverse-words-in-a-string/description/?envType=study-plan-v2&envId=leetcode-75
+
+const reverseWords = (str: string): string =>
+  str
+    .match(/[^\s]+/g)
+    ?.reverse()
+    .join(" ") || "";

LeetCode-75/07-238.ts

@@ -0,0 +1,24 @@
+// https://leetcode.com/problems/product-of-array-except-self/description/?envType=study-plan-v2&envId=leetcode-75
+
+const productExceptSelf = (nums: number[]): number[] => {
+  // O(N^2) SOLUTION
+  // return nums.map((_el, outerIdx) =>
+  //   nums.reduce((acc, val, idx) => (idx === outerIdx ? acc : acc * val), 1)
+  // );
+
+  // O(N) SOLUTION
+  const prefixes = new Array(nums.length).fill(1);
+  const postfixes = new Array(nums.length).fill(1);
+
+  for (let i = 0, prefix = 1; i < nums.length; i++) {
+    prefix *= nums[i];
+    prefixes[i] = prefix;
+  }
+
+  for (let i = nums.length - 1, postfix = 1; i >= 0; i--) {
+    postfix *= nums[i];
+    postfixes[i] = postfix;
+  }
+
+  return nums.map((_el, i) => (prefixes[i - 1] ?? 1) * (postfixes[i + 1] ?? 1));
+};

LeetCode-75/08-334.ts

@@ -0,0 +1,27 @@
+// https://leetcode.com/problems/increasing-triplet-subsequence/?envType=study-plan-v2&envId=leetcode-75
+
+const increasingTriplet = (nums: number[]): boolean => {
+  // O(N^3) SOLUTION
+  // if (nums.length < 3) return false;
+
+  // for (let i = 0; i < nums.length - 2; i++)
+  //   for (let j = i + 1; j < nums.length - 1; j++)
+  //     if (nums[j] > nums[i])
+  //       for (let k = j + 1; k < nums.length; k++)
+  //         if (nums[k] > nums[j]) return true;
+
+  // return false;
+
+  // O(N) SOLUTION
+  for (
+    let i = 0, firstMin = Number.MAX_VALUE, secondMin = Number.MAX_VALUE;
+    i < nums.length;
+    i++
+  ) {
+    if (nums[i] <= firstMin) firstMin = nums[i];
+    else if (nums[i] <= secondMin) secondMin = nums[i];
+    else return true;
+  }
+
+  return false;
+};

LeetCode-75/09-443.ts

@@ -0,0 +1,26 @@
+// https://leetcode.com/problems/string-compression/?envType=study-plan-v2&envId=leetcode-75
+
+const compress = (chars: string[]): number => {
+  if (!chars.length) return 0;
+
+  let compressed = "",
+    currChar = chars[0],
+    currCharCount = 1;
+
+  for (let i = 1; i < chars.length; i++) {
+    if (chars[i] === currChar) currCharCount++;
+    else {
+      compressed =
+        compressed + currChar + (currCharCount === 1 ? "" : currCharCount);
+      currChar = chars[i];
+      currCharCount = 1;
+    }
+  }
+
+  compressed =
+    compressed + currChar + (currCharCount === 1 ? "" : currCharCount);
+
+  for (let i = 0; i < compressed.length; i++) chars[i] = compressed[i];
+
+  return compressed.length;
+};