8.4 power set

Author: amejiarosario

src/08-dynamic-programming/power-set.js

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+/*
+ 8.4 Power Set: Write a method to return all subsets of a set.
+ */
+
+const bm = require('../05-bits/00-bit-manipulation');
+
+function getSubsets(set) {
+  const length = set.length;
+  const subsets = [];
+
+  for(let mask = 0; mask < Math.pow(2, length); mask++) {
+    const subset = [];
+
+    set.forEach((element, index) => {
+      if(bm.getBit(mask, index) > 0) {
+        subset.push(element);
+      }
+    });
+
+    subsets.push(subset);
+  }
+
+  return subsets;
+}
+
+module.exports = getSubsets;

src/08-dynamic-programming/power-set.spec.js

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+const expect = require('chai').expect;
+const getSubsets = require('./power-set');
+
+describe('getSubsets', function() {
+  it('1 stair', function () {
+    const set = [1, 2, 3];
+    expect(getSubsets(set)).to.eql([
+      [],
+      [1],
+      [2],
+      [1, 2],
+      [3],
+      [1, 3],
+      [2, 3],
+      [1, 2, 3]
+    ]);
+  });
+});