feat: pyramid algorithm

Author: francislagares

src/algorithms/pyramid/pyramid.ts

@@ -0,0 +1,39 @@
+// Option 1
+export const pyramid = (n: number) => {
+  const midpoint = Math.floor((2 * n - 1) / 2);
+
+  for (let row = 0; row < n; row++) {
+    let level = '';
+
+    for (let column = 0; column < 2 * n - 1; column++) {
+      if (midpoint - row <= column && midpoint + row >= column) {
+        level += '#';
+      } else {
+        level += ' ';
+      }
+    }
+
+    console.log(level);
+  }
+};
+
+// Option 2
+export const pyramidWithRecursion = (n: number, row = 0, level = '') => {
+  if (row === n) {
+    return;
+  }
+
+  if (level.length === 2 * n - 1) {
+    console.log(level);
+    return pyramidWithRecursion(n, row + 1);
+  }
+
+  const midpoint = Math.floor((2 * n - 1) / 2);
+  let add;
+  if (midpoint - row <= level.length && midpoint + row >= level.length) {
+    add = '#';
+  } else {
+    add = ' ';
+  }
+  pyramidWithRecursion(n, row, level + add);
+};

src/algorithms/pyramid/tests/pyramid.test.ts

@@ -0,0 +1,46 @@
+import { SpyInstance, describe, test, vi } from 'vitest';
+import { pyramid, pyramidWithRecursion } from '../pyramid';
+
+describe('Steps Algorithm', () => {
+  let spy: SpyInstance;
+
+  beforeEach(() => {
+    spy = vi.spyOn(console, 'log').mockImplementation(() => {});
+  });
+
+  afterEach(() => {
+    spy.mockRestore();
+  });
+
+  test('pyramid is a function', () => {
+    expect(typeof pyramid).toEqual('function');
+    expect(typeof pyramidWithRecursion).toEqual('function');
+  });
+
+  test('prints a pryamid for n = 2', () => {
+    pyramid(2);
+    pyramidWithRecursion(2);
+    expect(spy.mock.calls[0][0]).toEqual(' # ');
+    expect(spy.mock.calls[1][0]).toEqual('###');
+    expect(spy.mock.calls.length).toEqual(4);
+  });
+
+  test('prints a pryamid for n = 3', () => {
+    pyramid(3);
+    pyramidWithRecursion(3);
+    expect(spy.mock.calls[0][0]).toEqual('  #  ');
+    expect(spy.mock.calls[1][0]).toEqual(' ### ');
+    expect(spy.mock.calls[2][0]).toEqual('#####');
+    expect(spy.mock.calls.length).toEqual(6);
+  });
+
+  test('prints a pryamid for n = 4', () => {
+    pyramid(4);
+    pyramidWithRecursion(4);
+    expect(spy.mock.calls[0][0]).toEqual('   #   ');
+    expect(spy.mock.calls[1][0]).toEqual('  ###  ');
+    expect(spy.mock.calls[2][0]).toEqual(' ##### ');
+    expect(spy.mock.calls[3][0]).toEqual('#######');
+    expect(spy.mock.calls.length).toEqual(8);
+  });
+});