Added 7. lesson.

Author: Patakfalvi Krisztian Ext

07-stacks-and-queues/README.md

@@ -0,0 +1,9 @@
+## [Lesson 7 - Stacks and Queues](https://app.codility.com/programmers/lessons/7-stacks_and_queues/)
+
+- [**Brackets**](https://app.codility.com/programmers/lessons/7-stacks_and_queues/brackets/) - Determine whether a given string of parentheses (multiple types) is properly nested ([brackets.js](./brackets.js)) ([Codility Report](https://app.codility.com/demo/results/trainingRC3JDM-DZU/))
+
+- [**Fish**](https://app.codility.com/programmers/lessons/7-stacks_and_queues/fish/) - N voracious fish are moving along a river. Calculate how many fish are alive ([fish.js](./fish.js)) ([Codility Report](https://app.codility.com/demo/results/training5PYZPV-R4D/))
+
+- [**Nesting**](https://app.codility.com/programmers/lessons/7-stacks_and_queues/nesting/) - Determine whether a given string of parentheses (single type) is properly nested ([nesting.js](./nesting.js)) ([Codility Report](https://app.codility.com/demo/results/trainingSPCCTC-AUG/))
+
+- [**StoneWall**](https://app.codility.com/programmers/lessons/7-stacks_and_queues/stone_wall/) - Cover "Manhattan skyline" using the minimum number of rectangles ([stoneWall.js](./stoneWall.js)) ([Codility Report](https://app.codility.com/demo/results/training6QQDU3-GW5/))

07-stacks-and-queues/brackets.js

@@ -0,0 +1,21 @@
+function solution(S) {
+  const BRACKETS = { "(": ")", "{": "}", "[": "]" };
+  const OPENINGS = Object.keys(BRACKETS);
+  const stack = [];
+
+  for (let i = 0; i < S.length; i++) {
+    const char = S[i];
+
+    if (OPENINGS.includes(char)) {
+      stack.push(char);
+    } else if (BRACKETS[stack.pop()] !== char) {
+      return 0;
+    }
+  }
+
+  if (stack.length !== 0) {
+    return 0;
+  }
+
+  return 1;
+}

07-stacks-and-queues/fish.js

@@ -0,0 +1,26 @@
+function solution(A, B) {
+  const N = A.length;
+  const stack = [];
+
+  let count = 0;
+
+  for (let i = 0; i < N; i++) {
+    if (B[i] === 1) {
+      stack.push(A[i]);
+    } else {
+      if (stack.length === 0) {
+        count++;
+      } else {
+        while (stack.length && stack[stack.length - 1] < A[i]) {
+          stack.pop();
+        }
+
+        if (stack.length === 0) {
+          count++;
+        }
+      }
+    }
+  }
+
+  return count + stack.length;
+}

07-stacks-and-queues/nesting.js

@@ -0,0 +1,22 @@
+function solution(S) {
+  const N = S.length;
+  const stack = [];
+
+  for (let i = 0; i < N; i++) {
+    if (S[i] === "(") {
+      stack.push(")");
+    } else {
+      if (stack.length === 0) {
+        return 0;
+      } else {
+        stack.pop();
+      }
+    }
+  }
+
+  if (stack.length !== 0) {
+    return 0;
+  }
+
+  return 1;
+}

07-stacks-and-queues/stoneWall.js

@@ -0,0 +1,19 @@
+function solution(H) {
+  const N = H.length;
+  const stack = [];
+
+  let bricks = 0;
+
+  for (let i = 0; i < N; i++) {
+    while (stack.length && stack[stack.length - 1] > H[i]) {
+      stack.pop();
+    }
+
+    if (stack.length === 0 || stack[stack.length - 1] < H[i]) {
+      stack.push(H[i]);
+      bricks++;
+    }
+  }
+
+  return bricks;
+}

README.md

@@ -49,3 +49,13 @@ My JavaScript solutions to exercises and tests at [Codility](https://codility.co
 - [**NumberOfDiscIntersections**](https://app.codility.com/programmers/lessons/6-sorting/number_of_disc_intersections/) - Compute the number of intersections in a sequence of discs ([numberOfDiscIntersections.js](./06-sorting/numberOfDiscIntersections.js)) ([Codility Report](https://app.codility.com/demo/results/trainingVHCHHU-EDP/))
 
 - [**Triangle**](https://app.codility.com/programmers/lessons/6-sorting/triangle/) - Determine whether a triangle can be built from a given set of edges ([triangle.js](./06-sorting/triangle.js)) ([Codility Report](https://app.codility.com/demo/results/training35MRMB-C9Q/))
+
+## [Lesson 7 - Stacks and Queues](https://app.codility.com/programmers/lessons/7-stacks_and_queues/)
+
+- [**Brackets**](https://app.codility.com/programmers/lessons/7-stacks_and_queues/brackets/) - Determine whether a given string of parentheses (multiple types) is properly nested ([brackets.js](./07-stacks-and-queues/brackets.js)) ([Codility Report](https://app.codility.com/demo/results/trainingRC3JDM-DZU/))
+
+- [**Fish**](https://app.codility.com/programmers/lessons/7-stacks_and_queues/fish/) - N voracious fish are moving along a river. Calculate how many fish are alive ([fish.js](./07-stacks-and-queues/fish.js)) ([Codility Report](https://app.codility.com/demo/results/training5PYZPV-R4D/))
+
+- [**Nesting**](https://app.codility.com/programmers/lessons/7-stacks_and_queues/nesting/) - Determine whether a given string of parentheses (single type) is properly nested ([nesting.js](./07-stacks-and-queues/nesting.js)) ([Codility Report](https://app.codility.com/demo/results/trainingSPCCTC-AUG/))
+
+- [**StoneWall**](https://app.codility.com/programmers/lessons/7-stacks_and_queues/stone_wall/) - Cover "Manhattan skyline" using the minimum number of rectangles ([stoneWall.js](./07-stacks-and-queues/stoneWall.js)) ([Codility Report](https://app.codility.com/demo/results/training6QQDU3-GW5/))