Merge pull request #983 from gwbaik9717/main

[ganu] Week9

Author: gwbaik9717

find-minimum-in-rotated-sorted-array/gwbaik9717.js

@@ -0,0 +1,32 @@
+// Time complexity: O(logn)
+// Space complexity: O(1)
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var findMin = function (nums) {
+  let left = 0;
+  let right = nums.length - 1;
+
+  while (left < right) {
+    const mid = Math.floor((left + right) / 2);
+
+    if (nums.at(mid - 1) > nums.at(mid)) {
+      return nums[mid];
+    }
+
+    if (nums.at(mid + 1) < nums.at(mid)) {
+      return nums[mid + 1];
+    }
+
+    if (nums.at(mid + 1) > nums.at(right)) {
+      left = mid + 1;
+      continue;
+    }
+
+    right = mid - 1;
+  }
+
+  return nums[left];
+};

linked-list-cycle/gwbaik9717.js

@@ -0,0 +1,22 @@
+// Time complexity: O(n)
+// Space complexity: O(1)
+
+/**
+ * @param {ListNode} head
+ * @return {boolean}
+ */
+var hasCycle = function (head) {
+  let turtle = head;
+  let rabbit = head;
+
+  while (turtle && rabbit && rabbit.next) {
+    turtle = turtle.next;
+    rabbit = rabbit.next.next;
+
+    if (turtle === rabbit) {
+      return true;
+    }
+  }
+
+  return false;
+};

maximum-product-subarray/gwbaik9717.js

@@ -0,0 +1,31 @@
+// Time complexity: O(n)
+// Space complexity: O(n)
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var maxProduct = function (nums) {
+  let answer = nums[0];
+  const products = Array.from({ length: nums.length + 1 }, () => null);
+  products[0] = [1, 1]; // [min, max]
+
+  for (let i = 1; i < products.length; i++) {
+    const cases = [];
+
+    // case 1
+    cases.push(nums[i - 1]);
+
+    // case 2
+    cases.push(nums[i - 1] * products[i - 1][0]);
+
+    // case 3
+    cases.push(nums[i - 1] * products[i - 1][1]);
+
+    const product = [Math.min(...cases), Math.max(...cases)];
+    products[i] = product;
+    answer = Math.max(answer, product[1]);
+  }
+
+  return answer;
+};

minimum-window-substring/gwbaik9717.js

@@ -0,0 +1,75 @@
+// n: len(s), m: len(t)
+// Time complexity: O(n+m)
+// Space complexity: O(n+m)
+
+/**
+ * @param {string} s
+ * @param {string} t
+ * @return {string}
+ */
+var minWindow = function (s, t) {
+  let i = 0;
+  let j = 0;
+
+  const current = new Map();
+  const target = new Map();
+
+  current.set(s[i], 1);
+
+  for (const chr of t) {
+    if (target.has(chr)) {
+      target.set(chr, target.get(chr) + 1);
+      continue;
+    }
+
+    target.set(chr, 1);
+  }
+
+  let answer = null;
+
+  while (i < s.length) {
+    let pass = true;
+    for (const [key, value] of target) {
+      if (!current.has(key)) {
+        pass = false;
+        break;
+      }
+
+      if (current.get(key) < value) {
+        pass = false;
+        break;
+      }
+    }
+
+    if (pass) {
+      if (!answer) {
+        answer = s.slice(i, j + 1);
+      }
+
+      if (answer && j - i + 1 < answer.length) {
+        answer = s.slice(i, j + 1);
+      }
+
+      current.set(s[i], current.get(s[i]) - 1);
+      if (current.get(s[i]) === 0) {
+        current.delete(s[i]);
+      }
+      i++;
+
+      continue;
+    }
+
+    if (j < s.length) {
+      j++;
+      current.set(s[j], (current.get(s[j]) || 0) + 1);
+    } else {
+      break;
+    }
+  }
+
+  if (answer === null) {
+    return "";
+  }
+
+  return answer;
+};

pacific-atlantic-water-flow/gwbaik9717.js

@@ -0,0 +1,131 @@
+// n: height, m: width
+// Time complexity: O(n*m)
+// Space complexity: O(n*m)
+
+class _Queue {
+  constructor() {
+    this.q = [];
+    this.start = 0;
+    this.end = 0;
+  }
+
+  isEmpty() {
+    return this.start === this.end;
+  }
+
+  push(value) {
+    this.q.push(value);
+    this.end++;
+  }
+
+  pop() {
+    const rv = this.q[this.start];
+    delete this.q[this.start++];
+    return rv;
+  }
+}
+/**
+ * @param {number[][]} heights
+ * @return {number[][]}
+ */
+var pacificAtlantic = function (heights) {
+  const dy = [1, 0, -1, 0];
+  const dx = [0, 1, 0, -1];
+
+  const h = heights.length;
+  const w = heights[0].length;
+  const checked = Array.from({ length: h }, () =>
+    Array.from({ length: w }, () => [false, false])
+  );
+
+  // 태평양
+  const pacific = new _Queue();
+
+  for (let i = 0; i < h; i++) {
+    if (!checked[i][0][0]) {
+      pacific.push([i, 0]);
+      checked[i][0][0] = true;
+    }
+  }
+
+  for (let i = 0; i < w; i++) {
+    if (!checked[0][i][0]) {
+      pacific.push([0, i]);
+      checked[0][i][0] = true;
+    }
+  }
+
+  while (!pacific.isEmpty()) {
+    const [cy, cx] = pacific.pop();
+
+    for (let i = 0; i < dy.length; i++) {
+      const ny = cy + dy[i];
+      const nx = cx + dx[i];
+
+      if (
+        ny >= 0 &&
+        ny < h &&
+        nx >= 0 &&
+        nx < w &&
+        !checked[ny][nx][0] &&
+        heights[ny][nx] >= heights[cy][cx]
+      ) {
+        checked[ny][nx][0] = true;
+        pacific.push([ny, nx]);
+      }
+    }
+  }
+
+  // 대서양
+  const answer = [];
+  const atlantic = new _Queue();
+
+  for (let i = 0; i < h; i++) {
+    if (!checked[i][w - 1][1]) {
+      atlantic.push([i, w - 1]);
+      checked[i][w - 1][1] = true;
+    }
+
+    if (checked[i][w - 1][0] === true) {
+      answer.push([i, w - 1]);
+    }
+  }
+
+  for (let i = 0; i < w; i++) {
+    if (!checked[h - 1][i][1]) {
+      atlantic.push([h - 1, i]);
+      checked[h - 1][i][1] = true;
+
+      if (checked[h - 1][i][0] === true) {
+        answer.push([h - 1, i]);
+      }
+    }
+  }
+
+  while (!atlantic.isEmpty()) {
+    const [cy, cx] = atlantic.pop();
+
+    for (let i = 0; i < dy.length; i++) {
+      const ny = cy + dy[i];
+      const nx = cx + dx[i];
+
+      if (
+        ny >= 0 &&
+        ny < h &&
+        nx >= 0 &&
+        nx < w &&
+        !checked[ny][nx][1] &&
+        heights[ny][nx] >= heights[cy][cx]
+      ) {
+        if (checked[ny][nx][0] === true) {
+          answer.push([ny, nx]);
+        }
+
+        checked[ny][nx][1] = true;
+        atlantic.push([ny, nx]);
+      }
+    }
+  }
+
+  return answer;
+};