Abbreviation

Dynamic-Programming/Abbreviation.js

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+/**
+ * @description
+ * Given two strings, `a` and `b`, determine if it's possible to make `a` equal
+ * to `b` You can perform the following operations on the string `a`:
+ * 1. Capitalize zero or more of `a`'s lowercase letters.
+ * 2. Delete all the remaining lowercase letters in `a`.
+ *
+ * ### Algorithm
+ * The idea is in the problem statement itself: iterate through characters of
+ * string `a` and `b` (for character indexes `i` and `j` respectively):
+ * 1. If `a[i]` and `b[j]` are equal, then move to next position
+ * 2. If `a[i]` is lowercase of `b[j]`, then explore two possibilities:
+ * a) Capitalize `a[i]` or
+ * b) Skip `a[i]`
+ * 3. If the `a[i]` is not uppercase, just discard that character, else return
+ * `false`
+ *
+ * Time Complexity: (O(|a|*|b|)) where `|a|` => length of string `a`
+ *
+ * @param {String} a
+ * @param {String} b
+ * @returns {Boolean}
+ * @see https://www.hackerrank.com/challenges/abbr/problem - Related problem on HackerRank.
+ */
+export const abbreviation = (a, b) => {
+  const n = a.length
+  const m = b.length
+
+  let dp = Array.from({length: n + 1}, () => Array(m + 1).fill(false))
+  dp[0][0] = true
+
+  for (let i = 0; i < n; i++) {
+    for (let j = 0; j <= m; j++) {
+      if (dp[i][j]) {
+        if (j < m && a[i].toUpperCase() === b[j]) {
+          dp[i + 1][j + 1] = true
+        }
+        if (a[i] === a[i].toLowerCase()) {
+          dp[i + 1][j] = true
+        }
+      }
+    }
+  }
+
+  return dp[n][m]
+}

Dynamic-Programming/tests/Abbreviation.test.js

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+import { abbreviation } from '../Abbreviation.js'
+
+describe('Abbreviation', () => {
+  test('it can abbreviate string a to b', () => {
+    expect(abbreviation('', '')).toBe(true)
+    expect(abbreviation('a', '')).toBe(true)
+    expect(abbreviation('', 'A')).toBe(false)
+    expect(abbreviation('a', 'A')).toBe(true)
+    expect(abbreviation('abcDE', 'ABCDE')).toBe(true)
+    expect(abbreviation('ABcDE', 'ABCDE')).toBe(true)
+    expect(abbreviation('abcde', 'ABCDE')).toBe(true)
+    expect(abbreviation('abcde', 'ABC')).toBe(true)
+    expect(abbreviation('a', 'ABC')).toBe(false)
+    expect(abbreviation('abcXYdefghijKLmnopqrs', 'XYKL')).toBe(true)
+    expect(abbreviation('aBcXYdefghijKLmnOpqrs', 'XYKLOP')).toBe(false)
+    expect(abbreviation('abc123', 'ABC')).toBe(true)
+    expect(abbreviation('abc123', 'ABC123')).toBe(true)
+    expect(abbreviation('abc!@#def', 'ABC')).toBe(true)
+  })
+})