add: 只出现一次的数字等

test/math/ugly-number-ii.test.js

@@ -0,0 +1,7 @@
+import { nthUglyNumber } from '../../src/math/ugly-number-ii.js'
+
+test('丑数 II', () => {
+  expect(nthUglyNumber(9)).toBe(10)
+  expect(nthUglyNumber(1)).toBe(1)
+  expect(nthUglyNumber(10)).toBe(12)
+})