Merge branch 'release/1.4.0'

README.md

@@ -33,6 +33,8 @@ npm run test
 | 136 | [Single Number](/problems/single-number) | Easy | Hash table, bit manipulation |
 | 349 | [Intersection of Two Arrays](/problems/intersection-of-two-arrays) | Easy | Hash Table, two pointers, binary search, sort, set |
 | 1144 | [Decrease Elements To Make Array Zigzag](/problems/decrease-elements-to-make-array-zigzag) | Medium | Array |
+| 1150 | [Check If a Number Is Majority Element in a Sorted Array](/problems/is-a-a-majority-element) | Easy | Array, binary search |
+| 1153 | [String Transforms Into Another String](/problems/string-transforms-into-another-string) | Hard | Graph |
 
 ## Questions / Issues
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "leetcode",
-  "version": "1.3.0",
+  "version": "1.4.0",
   "description": "My solutions for LeetCode problems.",
   "main": "index.js",
   "scripts": {
@@ -28,5 +28,8 @@
     "eslint-plugin-promise": "^4.2.1",
     "eslint-plugin-standard": "^4.0.0",
     "jest": "^24.8.0"
+  },
+  "dependencies": {
+    "lodash": "^4.17.15"
   }
 }

problems/is-a-a-majority-element/README.md

@@ -0,0 +1,7 @@
+# Check If a Number Is Majority Element in a Sorted Array
+
+[Link to LeetCode page](https://leetcode.com/problems/is-a-a-majority-element/)
+
+Difficulty: Easy
+
+Topics: Array, binary search.

problems/is-a-a-majority-element/solution.js

@@ -0,0 +1,18 @@
+const isMajorityElement = (nums, target) => {
+  const minimum = nums.length / 2
+  let count = 0
+
+  for (const value of nums) {
+    if (value === target) {
+      count += 1
+    }
+
+    if (value > target) {
+      break
+    }
+  }
+
+  return (count > minimum)
+}
+
+module.exports = isMajorityElement

problems/is-a-a-majority-element/solution.test.js

@@ -0,0 +1,19 @@
+const isMajorityElement = require('./solution')
+
+test('Example 1', () => {
+  const nums = [2, 4, 5, 5, 5, 5, 5, 6, 6]
+  const target = 5
+
+  const result = isMajorityElement(nums, target)
+
+  expect(result).toBe(true)
+})
+
+test('Example 2', () => {
+  const nums = [10, 100, 101, 101]
+  const target = 101
+
+  const result = isMajorityElement(nums, target)
+
+  expect(result).toBe(false)
+})

problems/string-transforms-into-another-string/README.md

@@ -0,0 +1,7 @@
+# String Transforms Into Another String
+
+[Link to LeetCode page](https://leetcode.com/problems/string-transforms-into-another-string/)
+
+Difficulty: Hard
+
+Topics: Graph.

problems/string-transforms-into-another-string/solution.js

@@ -0,0 +1,83 @@
+const isEqual = require('lodash/isEqual')
+const difference = require('lodash/difference')
+
+const canConvert = (str1, str2) => {
+  if (str1 === str2) {
+    return true
+  }
+
+  const chars2 = [...str2]
+  const charMap2 = {}
+  const segment2 = [0]
+  for (let i = 0; i < chars2.length; i++) {
+    const char = chars2[i]
+
+    if (charMap2[char]) {
+      charMap2[char].push(i)
+    } else {
+      charMap2[char] = [i]
+    }
+
+    if (i > 0 && (chars2[i] !== chars2[i - 1])) {
+      segment2.push(i)
+    }
+  }
+
+  const chars1 = [...str1]
+  const charMap1 = {}
+  const segment1 = [0]
+  for (let i = 0; i < chars1.length; i++) {
+    const char = chars1[i]
+
+    if (charMap1[char]) {
+      charMap1[char].push(i)
+    } else {
+      charMap1[char] = [i]
+    }
+
+    if (i > 0 && (chars1[i] !== chars1[i - 1])) {
+      segment1.push(i)
+    }
+  }
+
+  const usedChars1 = Object.keys(charMap1).length
+  const usedChars2 = Object.keys(charMap2).length
+
+  if (usedChars1 === 26 && usedChars2 === 26) {
+    return false
+  }
+
+  if (usedChars1 < usedChars2) {
+    return false
+  }
+
+  if (segment1.length < segment2.length) {
+    return false
+  }
+
+  if (isEqual(segment1, segment2)) {
+    return true
+  }
+
+  for (const char2 in charMap2) {
+    const indexes = charMap2[char2]
+
+    for (const i of indexes) {
+      const char1 = chars1[i]
+      const char1indexes = charMap1[char1]
+
+      if (char1indexes.length > indexes.length) {
+        return false
+      }
+
+      const diff = difference(char1indexes, indexes)
+      if (diff.length > 0) {
+        return false
+      }
+    }
+  }
+
+  return true
+}
+
+module.exports = canConvert

problems/string-transforms-into-another-string/solution.test.js

@@ -0,0 +1,55 @@
+const canConvert = require('./solution')
+
+test('Example 1', () => {
+  const str1 = 'aabcc'
+  const str2 = 'ccdee'
+
+  const result = canConvert(str1, str2)
+
+  expect(result).toBe(true)
+})
+
+test('Example 2', () => {
+  const str1 = 'leetcode'
+  const str2 = 'codeleet'
+
+  const result = canConvert(str1, str2)
+
+  expect(result).toBe(false)
+})
+
+test('"ab" and "ba" should return true', () => {
+  const str1 = 'ab'
+  const str2 = 'ba'
+
+  const result = canConvert(str1, str2)
+
+  expect(result).toBe(true)
+})
+
+test('"abcdefghijklmnopqrstuvwxyz" and "abcdefghijklmnopqrstuvwxyz" should return true', () => {
+  const str1 = 'abcdefghijklmnopqrstuvwxyz'
+  const str2 = 'abcdefghijklmnopqrstuvwxyz'
+
+  const result = canConvert(str1, str2)
+
+  expect(result).toBe(true)
+})
+
+test('"abcdefghijklmnopqrstuvwxyz" and "bcdefghijklmnopqrstuvwxyza" should return false', () => {
+  const str1 = 'abcdefghijklmnopqrstuvwxyz'
+  const str2 = 'bcdefghijklmnopqrstuvwxyza'
+
+  const result = canConvert(str1, str2)
+
+  expect(result).toBe(false)
+})
+
+test('"abcdefghijklmnopqrstuvwxyz" and "bcdefghijklmnopqrstuvwxyzq" should return true', () => {
+  const str1 = 'abcdefghijklmnopqrstuvwxyz'
+  const str2 = 'bcdefghijklmnopqrstuvwxyzq'
+
+  const result = canConvert(str1, str2)
+
+  expect(result).toBe(true)
+})