add solution for ransom note

Author: sangtrandev00

src/leetcode/hash_table/ransom-note.test.ts

@@ -0,0 +1,40 @@
+import { describe, it, expect } from 'bun:test'
+import { canConstruct } from './ransom-note';
+
+describe('canConstruct', () => {
+    it('should return true when ransomNote can be constructed from magazine', () => {
+        expect(canConstruct('a', 'a')).toBe(true);
+        expect(canConstruct('aa', 'aab')).toBe(true);
+        expect(canConstruct('abc', 'cba')).toBe(true);
+    });
+
+    it('should return false when ransomNote cannot be constructed from magazine', () => {
+        expect(canConstruct('aa', 'ab')).toBe(false);
+        expect(canConstruct('aaa', 'aa')).toBe(false);
+        expect(canConstruct('abcd', 'abc')).toBe(false);
+    });
+
+    it('should return true for empty ransomNote', () => {
+        expect(canConstruct('', 'anystring')).toBe(true);
+    });
+
+    it('should return false for empty magazine when ransomNote is not empty', () => {
+        expect(canConstruct('a', '')).toBe(false);
+    });
+
+    it('should return true when both ransomNote and magazine are empty', () => {
+        expect(canConstruct('', '')).toBe(true);
+    });
+
+    it('should handle large inputs', () => {
+        const ransomNote = 'a'.repeat(1000);
+        const magazine = 'a'.repeat(1000);
+        expect(canConstruct(ransomNote, magazine)).toBe(true);
+
+        const magazineWithExtra = 'a'.repeat(1001);
+        expect(canConstruct(ransomNote, magazineWithExtra)).toBe(true);
+
+        const insufficientMagazine = 'a'.repeat(999);
+        expect(canConstruct(ransomNote, insufficientMagazine)).toBe(false);
+    });
+});

src/leetcode/hash_table/ransom-note.ts

@@ -0,0 +1,30 @@
+
+
+export function canConstruct(ransomNote: string, magazine: string): boolean {
+    if (magazine == '' && ransomNote == '') return true
+
+    const dictLetters: Record<string, number> = {}
+
+    for (let i = 0; i < magazine.length; i++) {
+        if (dictLetters[magazine[i]]) {
+            dictLetters[magazine[i]] += 1
+        } else {
+            dictLetters[magazine[i]] = 1
+        }
+    }
+
+    for (let i = 0; i < ransomNote.length; i++) {
+        if (dictLetters[ransomNote[i]]) {
+            if (dictLetters[ransomNote[i]] > 1) {
+                dictLetters[ransomNote[i]] -= 1
+            } else {
+                delete dictLetters[ransomNote[i]]
+            }
+        } else {
+            return false
+        }
+    }
+    return true    // Độ phức tạp
+
+
+};