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Discussion on: Javascript Sock Merchant Challenge - Solution 1

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bhaveshg profile image
BHAVESH GUPTA

A better approach:
Runtime: O(n)

  1. Take input array as A.
  2. Declare a dictionary, D.
  3. Iterate over A and store each values frequency as:

    if i exists in D, then D[i]=D[i]+1
    else, D[i]=1

  4. Iterate over D and sum half of each key-value pair.

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kurisutofu profile image
kurisutofu • Edited

Could we add 0.5 to avoid reiteration and round up when getting the value for a specific color?

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adyngom profile image
Ady Ngom

Reiteration is prevented by skipping to 2 indexes down if a match is found. I’m not clear on how 0.5 will help here since we are looking at full pairs values

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kurisutofu profile image
kurisutofu

Yes, you're right. I somehow didn't notice you were using i++ and i+=1.
Sorry.

The 0.5 comment was regarding Bavesh's step 4, sorry I was not clear.

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adyngom profile image
Ady Ngom

Hello Bhavesh, thank you for your input. This is the first solution and not necessarily the most performant one as I have stated in the video. If you look at the gist that was created for this project here Sock merchant solutions you will that the second solution that is coming in part 2 is using the dictionary approach tou have suggested


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javascript
function stockAndCount( n, arr ) {
let pairs = 0;
const colors = arr.reduce((acc, val) => {
(!!acc[val]) ? acc[val] += 1 : acc[val] = 1;
return acc;
}, {});

Object.keys(colors).forEach( n => {
    let _pair = parseInt( colors[n] / 2);
    if ( _pair >= 1 ) pairs += _pair;
});

return pairs;
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}


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Since this is unassuming of who is watching and what the level is, I start with the simple easy to grasp and evolve to the 'better' solution, better being relative here.

Stay tuned for the next episode and the reasoning why solution 2 will be a better approach.

Cheers

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bhaveshg profile image
BHAVESH GUPTA

Good work, Sir.