add: 只出现一次的数字等

test/array/reverse-pairs.test.js

@@ -0,0 +1,29 @@
+import {
+  reversePairs,
+  merge,
+  mergeSort,
+  resetCount
+} from '../../src/array/reverse-pairs'
+
+describe('逆序对', () => {
+  beforeEach(() => {
+    resetCount()
+  })
+
+  test('归并排序 - 合并左右', () => {
+    expect(merge([7], [5])).toEqual([5, 7])
+    expect(merge([2], [3])).toEqual([2, 3])
+    expect(merge([2, 3], [4, 5])).toEqual([2, 3, 4, 5])
+  })
+
+  test('归并排序', () => {
+    expect(mergeSort([2, 4, 3, 5])).toEqual([2, 3, 4, 5])
+    expect(mergeSort([2, 4, 3, 0])).toEqual([0, 2, 3, 4])
+  })
+
+  test('逆序对', () => {
+    expect(reversePairs([7, 5, 6, 4])).toBe(5)
+    expect(reversePairs([2, 4, 1, 3, 5])).toBe(3)
+    expect(reversePairs([1, 2, 3, 4])).toBe(0)
+  })
+})