add MaxProductOfThree

Author: talgat-ruby

README.md

@@ -25,6 +25,8 @@
         -   [GenomicRangeQuery](#s_5_genomic_range_query)
         -   [MinAvgTwoSlice](#s_5_min_avg_two_slice)
         -   [CountDiv](#s_5_count_div)
+    -   [Lesson 6 - Sorting](#s_6)
+        -   [MaxProductOfThree](#s_6_max_product_of_three)
 -   [Licence](#licence)
 
 <a name="installation"></a>
@@ -239,6 +241,22 @@ https://github.com/talgat-ruby/codility-lessons-javascript/blob/master/lesson5_p
 
 https://app.codility.com/demo/results/trainingP6XQJ7-KM7/
 
+<a name="s_6"></a>
+
+### Lesson 6 - Sorting
+
+<a name="s_6_max_product_of_three"></a>
+
+#### MaxProductOfThree
+
+##### File
+
+https://github.com/talgat-ruby/codility-lessons-javascript/blob/master/lesson6_sorting/MaxProductOfThree.js
+
+##### Link to Report
+
+https://app.codility.com/demo/results/trainingWJKGRA-8JV/
+
 <a name="licence"></a>
 
 ## License

lesson6_sorting/MaxProductOfThree.js

@@ -0,0 +1,34 @@
+function solution(A) {
+    let max1 = -1001;
+    let max2 = -1001;
+    let max3 = -1001;
+    let min1 = 1001;
+    let min2 = 1001;
+
+    for (const a of A) {
+        if (a > max1) {
+            [max3, max2, max1] = [max2, max1, a];
+        } else if (a > max2) {
+            [max3, max2] = [max2, a];
+        } else if (a > max3) {
+            max3 = a;
+        }
+
+        if (a < min1) {
+            [min2, min1] = [min1, a];
+        } else if (a < min2) {
+            min2 = a;
+        }
+    }
+
+    const tot1 = max2 * max3;
+    const tot2 = min1 * min2;
+
+    if (max1 >= 0 && tot2 > tot1) {
+        return tot2 * max1;
+    } else {
+        return tot1 * max1;
+    }
+}
+
+module.exports = solution;

lesson6_sorting/MaxProductOfThree.test.js

@@ -0,0 +1,7 @@
+const solution = require("./MaxProductOfThree");
+
+describe("test MaxProductOfThree", () => {
+    test("[-3, 1, 2, -2, 5, 6] -> 60", () => {
+        expect(solution([-3, 1, 2, -2, 5, 6])).toBe(60);
+    });
+});