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<!DOCTYPE html>
<html lang="en" class="dark">

<head>

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  <title>Subsets | DSA Portfolio</title>

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<body class="bg-slate-950 text-white font-inter">

  <!-- Header -->
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    <div class="max-w-7xl mx-auto px-6 py-5">

      <a href="../index.html"
        class="text-cyan-400">
        ← Back to Portfolio
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  </header>

  <!-- Main -->
  <main class="max-w-7xl mx-auto px-6 py-16 grid lg:grid-cols-3 gap-10">

    <!-- Content -->
    <section class="lg:col-span-2">

      <p class="text-cyan-400 font-mono">
        Recursion / Backtracking
      </p>

      <h1 class="text-5xl font-black mt-4">
        Subsets
      </h1>

      <p class="text-slate-400 mt-6 text-lg">
        Generate all possible subsets of a given array using recursion and backtracking.
      </p>

      <!-- Intuition -->
      <div class="mt-14">

        <h2 class="text-3xl font-bold">
          Intuition
        </h2>

        <p class="text-slate-300 mt-5 leading-8">
          For every element we have two choices:
          either include it in the subset or exclude it.
          This naturally forms a recursion tree.
        </p>

      </div>

      <!-- Algorithm -->
      <div class="mt-14">

        <h2 class="text-3xl font-bold">
          Algorithm
        </h2>

        <ol class="mt-5 space-y-3 text-slate-300 list-decimal list-inside">

          <li>Start recursion from index 0</li>

          <li>Include current element</li>

          <li>Move to next index</li>

          <li>Backtrack by removing element</li>

          <li>Exclude current element</li>

        </ol>

      </div>

      <!-- Dry Run -->
      <div class="mt-14">

        <h2 class="text-3xl font-bold">
          Dry Run
        </h2>

        <div class="mt-5 p-6 rounded-2xl bg-white/5 border border-white/10 font-mono">

          [] <br>
          [1] <br>
          [1,2] <br>
          [2]

        </div>

      </div>

      <!-- Code -->
      <div class="mt-14">

        <h2 class="text-3xl font-bold">
          Python Solution
        </h2>

        <pre
          class="mt-5 p-6 rounded-2xl bg-black overflow-x-auto border border-white/10 text-sm code-block">

<code>
class Solution:

    def subsets(self, nums):

        ans = []

        def backtrack(i, curr):

            if i == len(nums):

                ans.append(curr[:])
                return

            curr.append(nums[i])

            backtrack(i + 1, curr)

            curr.pop()

            backtrack(i + 1, curr)

        backtrack(0, [])

        return ans
</code>

        </pre>

      </div>

    </section>

    <!-- Sidebar -->
    <aside>

      <div class="sticky top-10 p-6 rounded-3xl bg-white/5 border border-white/10">

        <h2 class="text-2xl font-bold">
          Problem Info
        </h2>

        <div class="mt-8 space-y-5">

          <div>
            <p class="text-slate-400 text-sm">
              Difficulty
            </p>

            <p class="text-yellow-400 font-semibold">
              Medium
            </p>
          </div>

          <div>
            <p class="text-slate-400 text-sm">
              Topic
            </p>

            <p>
              Recursion
            </p>
          </div>

          <div>
            <p class="text-slate-400 text-sm">
              Time Complexity
            </p>

            <p>
              O(2^n)
            </p>
          </div>

          <div>
            <p class="text-slate-400 text-sm">
              Space Complexity
            </p>

            <p>
              O(n)
            </p>
          </div>

          <div>
            <p class="text-slate-400 text-sm">
              Platform
            </p>

            <p>
              LeetCode
            </p>
          </div>

          <div>
            <p class="text-slate-400 text-sm">
              Date Solved
            </p>

            <p>
              2026-05-08
            </p>
          </div>

        </div>

      </div>

    </aside>

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