merge: Add FindMinIterator algorithm (#928)

* FindMinIterator

Do the `standard` thing.

Rename `FindMin` to `FindMinIterator`

Rename to `FindMinIterator`

Pull `FindMin` from `master`

* Remove these separator comments.

Co-authored-by: RuSaG0 <mirzoev-ruslan-2000@mail.ru>

Maths/FindMinIterator.js

@@ -0,0 +1,36 @@
+/**
+ * @function FindMinIterator
+ * @description Function to find the minimum number given in an array.
+ */
+
+const FindMinIterator = (_iterable, _selector = undefined) => {
+  let min
+
+  const iterator = _iterable[Symbol.iterator]()
+  if (!_selector) {
+    let current = iterator.next()
+    if (current.done) { return undefined }
+    min = current.value
+
+    current = iterator.next()
+    while (!current.done) {
+      const x = current.value
+      if (x < min) { min = x }
+      current = iterator.next()
+    }
+  } else {
+    let current = iterator.next()
+    if (current.done) { return undefined }
+    min = _selector(current.value)
+
+    current = iterator.next()
+    while (!current.done) {
+      const x = _selector(current.value)
+      if (x < min) { min = x }
+      current = iterator.next()
+    }
+  }
+  return min
+}
+
+export { FindMinIterator }

Maths/test/FindMinIterator.test.js

@@ -0,0 +1,54 @@
+import { FindMinIterator } from '../FindMinIterator'
+
+describe('FindMinIterator', () => {
+  test('given empty array then min is undefined', () => {
+    expect(FindMinIterator([])).toBeUndefined()
+  })
+
+  test('given single value array then min is found', () => {
+    expect(FindMinIterator([1])).toBe(1)
+    expect(FindMinIterator([-1])).toBe(-1)
+    expect(FindMinIterator([0])).toBe(0)
+  })
+
+  test('given array then min is found', () => {
+    expect(FindMinIterator([1, 2])).toBe(1)
+    expect(FindMinIterator([-1, 10])).toBe(-1)
+    expect(FindMinIterator([0, 100])).toBe(0)
+    expect(FindMinIterator([100, 0])).toBe(0)
+    expect(FindMinIterator([100, 50, 20, 0, -100, 0, 2, 30, 45, 99, 104, 23])).toBe(-100)
+  })
+
+  test('given empty generator then min is undefined', () => {
+    const src = function* () { } // eslint-disable-line
+    expect(FindMinIterator(src())).toBeUndefined()
+  })
+
+  test('given generator then min is found', () => {
+    const src = function* () { // eslint-disable-line
+      yield 1
+      yield -1
+      yield 0
+    }
+    expect(FindMinIterator(src())).toBe(-1)
+  })
+
+  test('given string generator then min string length is found', () => {
+    const src = function* () { // eslint-disable-line
+      yield 'abc'
+      yield 'de'
+      yield 'qwerty'
+    }
+    expect(FindMinIterator(src(), _x => _x.length)).toBe(2)
+  })
+
+  test('given array of objects then min accessor is found', () => {
+    const array = [
+      { name: 'Item #1', price: 1.0 },
+      { name: 'Item #2', price: 0.0 },
+      { name: 'Item #3', price: -1.0 }
+    ]
+    expect(FindMinIterator(array, _x => _x.price)).toBe(-1)
+    expect(FindMinIterator(array, _x => _x.name)).toBe('Item #1')
+  })
+})