CodeWithWho

Building software that solves real problems.
Software Engineer | Frontend | Backend
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[CodeWithWho @CodeWithWho]

Yesterday I wore an article on how my last week went
Its is posted on LinkedIn

https://t.co/82S2GUJ6BH

[CodeWithWho @CodeWithWho]

Real inventory systems maintain item → available quantity and decrement as demand arrives. That's exactly what this hash-table solution is doing. #softwareengineering Watch: https://t.co/UrHo5rOh8n

[CodeWithWho @CodeWithWho]

Required character missing or count already zero? Return False. No full magazine scan needed. #hashtables #optimization Watch: https://t.co/UrHo5rOh8n

[CodeWithWho @CodeWithWho]

Magazine = inventory. Letter = demand. Every required character simply decrements its available count. #algorithms #hashtables Watch: https://t.co/UrHo5rOh8n

[CodeWithWho @CodeWithWho]

M='aabc' becomes inventory: a→2, b→1, c→1. We no longer care where the characters are — only how many remain. #hashtables #python Watch: https://t.co/UrHo5rOh8n

[CodeWithWho @CodeWithWho]

Brute force asks: where is another unused character? Optimized asks: how many do I have left? That shift changes the whole solution. #hashtables #algorithms Watch: https://t.co/UrHo5rOh8n

[CodeWithWho @CodeWithWho]

Bad inventory flow: search stock records again for every unit. Better flow: item → available count → decrement. Same optimization idea. #softwareengineering Watch: https://t.co/qpq1NQgWjz

[CodeWithWho @CodeWithWho]

We track used positions, but what we really need is available quantity by character. That is the clue toward hashing. #hashtables #optimization Watch: https://t.co/qpq1NQgWjz

[CodeWithWho @CodeWithWho]

Worst case, used stores every magazine index. That gives O(M) auxiliary space. #python #bigO Watch: https://t.co/qpq1NQgWjz

[CodeWithWho @CodeWithWho]

If L ≈ M ≈ n, then O(L × M) becomes O(n²). Repeated scans create the quadratic growth. #algorithms Watch: https://t.co/qpq1NQgWjz

[CodeWithWho @CodeWithWho]

Why O(L × M)? Every required character in L may trigger a full scan through M. #algorithms #bigO Watch: https://t.co/qpq1NQgWjz

[CodeWithWho @CodeWithWho]

The code is correct, but every requirement can trigger another scan. Correctness and efficiency are two different questions. #algorithms Watch: https://t.co/C3XuxAvNTX

[CodeWithWho @CodeWithWho]

Second 'a': index 0 matches but is already used, so the search continues to index 1. #python #algorithms Watch: https://t.co/C3XuxAvNTX

[CodeWithWho @CodeWithWho]

Next requirement, inner loop starts again. The debugger makes the repeated magazine scan obvious. #algorithms #optimization Watch: https://t.co/C3XuxAvNTX

[CodeWithWho @CodeWithWho]

First 'a': match M[0] → add 0 to used → found=True → break. One requirement consumes one copy. #python #debugging Watch: https://t.co/C3XuxAvNTX

[CodeWithWho @CodeWithWho]

Debugger focus: char_l, j, used, found. Those 4 values show the entire brute-force search at runtime. #python #debugging Watch: https://t.co/C3XuxAvNTX

[CodeWithWho @CodeWithWho]

The code is correct, but every requirement can trigger another scan. Correctness and efficiency are two different questions. #algorithms Watch: https://t.co/BX20JzJBdO

[CodeWithWho @CodeWithWho]

Second 'a': index 0 matches but is already used, so the search continues to index 1. #python #algorithms Watch: https://t.co/BX20JzJBdO

[CodeWithWho @CodeWithWho]

Next requirement, inner loop starts again. The debugger makes the repeated magazine scan obvious. #algorithms #optimization Watch: https://t.co/BX20JzJBdO

[CodeWithWho @CodeWithWho]

@RyanJ_KOL Yes a frequency map will help if we are only concerned about count

But that is where the hash comes in for the brute force iteration is the key to showing waste

[CodeWithWho @CodeWithWho]

Why track indexes? In M='aba', index 0 and index 2 are two separate copies of 'a'. Each can be consumed once. #python #algorithms

[CodeWithWho @CodeWithWho]

Debugger focus: char_l, j, used, found. Those 4 values show the entire brute-force search at runtime. #python #debugging Watch: https://t.co/BX20JzJBdO