[C++ Solutions for Dynamic Programming] Climbing Stairs

Climbing Stairs

1. Code

• Each time you can either climb 1 or 2 steps

class Solution {
public:
    int climbStairs(int n) {
        if (n == 1) return 1;
        if (n == 2) return 2;

        int prev1 = 2;
        int prev2 = 1;
        int current = 0;

        for (int i = 3;i < n+1; i++) {
            current = prev1 + prev2;
            prev2 = prev1;
            prev1 = current;
        }
        return prev1;
    }
};

Reviews

1. Fibonacci

• The problem is similar to calculating the Fibonacci sequence becuase it has a structure where the current state is calcuated based on the previous states

• The reason why

  \[ways(n) = ways(n-1) + ways(n+2)\]

  1. n-1 step, adding 1 step will take you to the n-th step

  2. n-2 step, adding 2 steps will take you to the n-th step

     So, n-th step is the sum of all the ways to reach n-1 step + n-2 step

Github Blog (Customize the tag page)

1. Uppercase in Tag Slugs (generate_tags.rb)

• gsub to convert spaces in tags to hyphens (-), while preserving case.

• Tags like API will now correctly generate pages with their original case (i.e., API, not api)

module Jekyll
  class TagPageGenerator < Generator
    safe true

    def generate(site)
      site.tags.each do |tag, posts|
        # Use slugify with 'raw' mode to preserve case
        slug = tag.gsub(' ', '-').gsub(/[^\w-]/, '') # Keep the original case in the slug
        site.pages << TagPage.new(site, site.source, File.join('tags', slug), tag)
      end
    end
  end

  class TagPage < Page
    def initialize(site, base, dir, tag)
      @site = site
      @base = base
      @dir = dir
      @name = 'index.html'

      self.process(@name)
      self.read_yaml(File.join(base, '_layouts'), 'tag.html')
      self.data['tag'] = tag
      self.data['title'] = "Posts tagged as \"#{tag}\""
    end
  end
end

2. Update Tag URL (post.html)

• Jekyll slugify method converts tags to lowercase. So, add the mode : 'raw' option, which preserves the original case

<!-- tags -->

  <div class="post-tags">
    <i class="fa fa-tags fa-fw me-1"></i>
    
      <a
        href="/tags/c%2B%2B/"
        class="post-tag no-text-decoration"
      >c++<!-- Display the tag as-is, preserving case -->
      </a>
    
      <a
        href="/tags/python/"
        class="post-tag no-text-decoration"
      >python<!-- Display the tag as-is, preserving case -->
      </a>
    
      <a
        href="/tags/algorithm/"
        class="post-tag no-text-decoration"
      >algorithm<!-- Display the tag as-is, preserving case -->
      </a>
    
      <a
        href="/tags/jekyll/"
        class="post-tag no-text-decoration"
      >jekyll<!-- Display the tag as-is, preserving case -->
      </a>
    
  </div>

3. Modifying to Exclude Tag Pages (page.html)

• page.html layout, which includes a dynamic-title, was conflicting with the tag pages (causing duplicate titles)

• To fix this, I added a condition to exclude tag pages from displaying the dynamic-title