Create findRelativeMaximumPointCount.js

Data-Structures/Array/NumberOfLocalMaximumPoints.js

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+/**
+ * [NumberOfLocalMaximumPoints](https://www.geeksforgeeks.org/find-indices-of-all-local-maxima-and-local-minima-in-an-array/) is an algorithm to find relative bigger numbers compared to their neighbors
+ *
+ * Notes:
+ * - like the other similar local maxima search function find relative maxima points in array but doesnt stop at one but returns total point count
+ * - runs on array A of size n and returns the local maxima count using divide and conquer methodology
+ *
+ * @complexity: O(n) (on average )
+ * @complexity: O(n) (worst case)
+ * @flow
+ */
+
+// check if returned index is a local maxima
+const IsMaximumPoint = (array, index) => {
+    // handle array bounds
+    // array start
+    if(index == 0) {
+        return array[index] > array[index + 1];
+    // array end
+    } else if(index == array.length - 1) {
+        return array[index] > array[index - 1];
+    // handle index inside array bounds
+    } else {
+        return array[index] > array[index + 1] && array[index] > array[index - 1];
+    }
+}
+
+const CountLocalMaximumPoints = (array, startIndex, endIndex) => {
+    // stop check in divide and conquer recursion
+    if(startIndex == endIndex) {
+        return IsMaximumPoint(array, startIndex) ? 1 : 0;
+    }
+
+    // handle the two halves
+    let middleIndex = parseInt((startIndex + endIndex) / 2);
+    return CountLocalMaximumPoints(array, startIndex, middleIndex) + 
+    CountLocalMaximumPoints(array, middleIndex + 1, endIndex);
+}
+
+const NumberOfLocalMaximumPoints = (A) => CountLocalMaximumPoints(A, 0, A.length - 1);
+
+export { NumberOfLocalMaximumPoints } 

Data-Structures/Array/NumberOfLocalMaximumPoints.test.js

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+import { NumberOfLocalMaximumPoints } from './NumberOfLocalMaximumPoints'
+
+describe('LocalMaximomPoint tests', () => {
+  it('test boundry maximom points - last element', () => {
+    const Array = [1, 2, 3, 4, 5, 6, 12];
+    expect(NumberOfLocalMaximumPoints(Array)).toEqual(1)
+  })
+
+  it('test boundry maximom points - first element', () => {
+    const Array = [13,6,5,4,3,2,1];
+    expect(NumberOfLocalMaximumPoints(Array)).toEqual(1)
+  })
+
+  it('test boundry maximom points - both boundries have maximom points', () => {
+    // Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
+    const Array = [13, 2, 3, 4, 5, 6, 12];
+    expect(NumberOfLocalMaximumPoints(Array)).toEqual(2)
+  })
+
+  it('multiple maximom points in the middle', () => {
+    // Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
+    const Array = [1,3,2,5,6,9,2,7,12,1,0];
+    expect(NumberOfLocalMaximumPoints(Array)).toEqual(3)
+  })
+
+  it('multiple maximom points in the middle with one at end', () => {
+    // Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
+    const Array = [1,3,2,5,6,9,2,7,12,1,10];
+    expect(NumberOfLocalMaximumPoints(Array)).toEqual(4)
+  })
+
+  it('multiple maximom points in the middle with one at start', () => {
+    // Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
+    const Array = [10,3,2,5,6,9,2,7,12,1,0];
+    expect(NumberOfLocalMaximumPoints(Array)).toEqual(3)
+  })
+
+  it('multiple maximom points in the middle with two more at both ends', () => {
+    // Test a mix of number types (i.e., positive/negative, numbers with decimals, fractions)
+    const Array = [10,3,11,5,6,9,2,7,12,1,10];
+    expect(NumberOfLocalMaximumPoints(Array)).toEqual(5)
+  })
+})