add StoneWall

Author: talgat-ruby

README.md

@@ -34,6 +34,7 @@
         -   [Brackets](#s_7_brackets)
         -   [Fish](#s_7_fish)
         -   [Nesting](#s_7_nesting)
+        -   [StoneWall](#s_7_stone_wall)
 -   [Licence](#licence)
 
 <a name="installation"></a>
@@ -328,6 +329,18 @@ https://github.com/talgat-ruby/codility-lessons-javascript/blob/master/lesson7_s
 
 https://app.codility.com/demo/results/trainingG7NMTC-FKF/
 
+<a name="s_7_stone_wall"></a>
+
+#### StoneWall
+
+##### File
+
+https://github.com/talgat-ruby/codility-lessons-javascript/blob/master/lesson7_stacks_and_queues/StoneWall.js
+
+##### Link to Report
+
+https://app.codility.com/demo/results/trainingDRUBXQ-4DF/
+
 <a name="licence"></a>
 
 ## License

lesson7_stacks_and_queues/StoneWall.js

@@ -0,0 +1,28 @@
+function solution(H) {
+    let counter = 1;
+    let set = new Set([H[0]]);
+    let min = null;
+
+    for (let i = 1; i < H.length; i++) {
+        const h = H[i];
+        if (H[i - 1] < h) {
+            if (min !== null) {
+                const arr = [...set];
+                const ind = arr.findIndex(a => a > min);
+                set = new Set([...arr.slice(0, ind), min]);
+                min = null;
+            }
+            set.add(h);
+            counter++;
+        } else if (H[i - 1] > h) {
+            min = h;
+            if (!set.has(h)) {
+                counter++;
+            }
+        }
+    }
+
+    return counter;
+}
+
+module.exports = solution;

lesson7_stacks_and_queues/StoneWall.test.js

@@ -0,0 +1,10 @@
+const solution = require("./StoneWall");
+
+describe("test StoneWall", () => {
+    test("[8, 8, 5, 7, 9, 8, 7, 4, 8] -> 7", () => {
+        expect(solution([8, 8, 5, 7, 9, 8, 7, 4, 8])).toBe(7);
+    });
+    test("[2, 5, 1, 4, 6, 7, 9, 10, 1] -> 8", () => {
+        expect(solution([2, 5, 1, 4, 6, 7, 9, 10, 1])).toBe(8);
+    });
+});