[이병현] Week 4

longest-consecutive-sequence/tolluset.ts

@@ -0,0 +1,42 @@
+/*
+ * TC: O(n)
+ * SC: O(n)
+ * */
+function longestConsecutive(nums: number[]): number {
+  const n = nums.length;
+
+  if (n <= 1) {
+    return n;
+  }
+
+  const numsSet = new Set(nums);
+  let longestLen = 0;
+
+  for (let i = 0; i < n; i++) {
+    let current = nums[i];
+
+    if (!numsSet.has(current - 1)) {
+      let currentLen = 1;
+
+      while (numsSet.has(current + 1)) {
+        current++;
+        currentLen++;
+      }
+
+      longestLen = Math.max(longestLen, currentLen);
+    }
+  }
+  return longestLen;
+}
+
+const t1 = longestConsecutive([100, 4, 200, 1, 3, 2]);
+console.info("🚀 : tolluset.ts:5: t1=", t1); // 4
+
+const t2 = longestConsecutive([0, 3, 7, 2, 5, 8, 4, 6, 0, 1]);
+console.info("🚀 : tolluset.ts:8: t2=", t2); // 9
+
+const t3 = longestConsecutive([9, 1, 4, 7, 3, -1, 0, 5, 8, -1, 6]);
+console.info("🚀 : tolluset.ts:40: t3=", t3); // 7
+
+const t4 = longestConsecutive([-6, -1, -1, 9, -8, -6, -6, 4, 4, -3, -8, -1]);
+console.info("🚀 : tolluset.ts:59: t4=", t4); // 1

maximum-subarray/tolluset.ts

@@ -0,0 +1,39 @@
+/*
+ * TC: O(n)
+ * SC: O(1)
+ * */
+function maxProduct(nums: number[]): number {
+  const n = nums.length;
+
+  if (n === 1) {
+    return nums[0];
+  }
+
+  let max = 0,
+    min = 0,
+    res = 0;
+
+  for (let i = 0; i < n; i++) {
+    const cur = nums[i];
+
+    if (cur < 0) {
+      [max, min] = [min, max];
+    }
+
+    max = Math.max(cur, max * cur);
+    min = Math.min(cur, min * cur);
+
+    res = Math.max(res, max);
+  }
+
+  return res;
+}
+
+const t1 = maxProduct([2, 3, -2, 4]);
+console.info("🚀 : tolluset.ts:3: t1=", t1); // 6
+
+const t2 = maxProduct([-2, 0, -1]);
+console.info("🚀 : tolluset.ts:6: t2=", t2); // 0
+
+const t3 = maxProduct([-2]);
+console.info("🚀 : tolluset.ts:34: t3=", t3); // -2

missing-number/tolluset.ts

@@ -0,0 +1,21 @@
+/*
+ * TC: O(n)
+ * SC: O(1)
+ * */
+function missingNumber(nums: number[]): number {
+  const n = nums.length;
+
+  const sum = (n * (n + 1)) / 2;
+  const actualSum = nums.reduce((acc, curr) => acc + curr, 0);
+
+  return sum - actualSum;
+}
+
+const t1 = missingNumber([3, 0, 1]);
+console.info("🚀 : tolluset.ts:3: t1=", t1); // 2
+
+const t2 = missingNumber([0, 1]);
+console.info("🚀 : tolluset.ts:6: t2=", t2); // 2
+
+const t3 = missingNumber([9, 6, 4, 2, 3, 5, 7, 0, 1]);
+console.info("🚀 : tolluset.ts:9: t3=", t3); // 8

valid-palindrome/tolluset.ts

@@ -0,0 +1,29 @@
+/*
+ * TC: O(n)
+ * SC: O(n)
+ * */
+function isPalindrome(s: string): boolean {
+  const parsedString = s.replace(/[^A-Za-z0-9]/g, "").toLowerCase();
+  const n = parsedString.length;
+
+  if (n === 0) {
+    return true;
+  }
+
+  for (let i = 0; i < n / 2; i++) {
+    if (parsedString[i] !== parsedString[n - i - 1]) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+const t1 = isPalindrome("A man, a plan, a canal: Panama");
+console.info("🚀 : tolluset.ts:18: t1=", t1); // true
+
+const t2 = isPalindrome("race a car");
+console.info("🚀 : tolluset.ts:21: t2=", t2); // false
+
+const t3 = isPalindrome(" ");
+console.info("🚀 : tolluset.ts:24: t3=", t3); // ture

word-search/tolluset.ts

@@ -0,0 +1,83 @@
+/*
+ * TC: O(row * column * 4^words.length)
+ * SC: O(n)
+ * */
+function exist(board: string[][], word: string): boolean {
+  const words = word.split("");
+  const n = words.length;
+
+  const rowLen = board.length;
+  const columnLen = board[0].length;
+
+  const dfs = (row: number, column: number, cursor: number) => {
+    if (cursor === n) {
+      return true;
+    }
+
+    if (
+      row < 0 ||
+      row >= rowLen ||
+      column < 0 ||
+      column >= columnLen ||
+      board[row][column] !== words[cursor]
+    ) {
+      return false;
+    }
+
+    const current = board[row][column];
+    board[row][column] = "";
+
+    if (
+      dfs(row - 1, column, cursor + 1) ||
+      dfs(row + 1, column, cursor + 1) ||
+      dfs(row, column - 1, cursor + 1) ||
+      dfs(row, column + 1, cursor + 1)
+    ) {
+      return true;
+    }
+
+    board[row][column] = current;
+
+    return false;
+  };
+
+  for (let row = 0; row < rowLen; row++) {
+    for (let column = 0; column < columnLen; column++) {
+      if (dfs(row, column, 0)) {
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
+const t1 = exist(
+  [
+    ["A", "B", "C", "E"],
+    ["S", "F", "C", "S"],
+    ["A", "D", "E", "E"],
+  ],
+  "ABCCED",
+);
+console.info("🚀 : tolluset.ts:5: t1=", t1); // true
+
+const t2 = exist(
+  [
+    ["A", "B", "C", "E"],
+    ["S", "F", "C", "S"],
+    ["A", "D", "E", "E"],
+  ],
+  "SEE",
+);
+console.info("🚀 : tolluset.ts:15: t2=", t2); // true
+
+const t3 = exist(
+  [
+    ["A", "B", "C", "E"],
+    ["S", "F", "C", "S"],
+    ["A", "D", "E", "E"],
+  ],
+  "ABCB",
+);
+console.info("🚀 : tolluset.ts:24: t3=", t3); // false