Grind 75 Question 25: Contains Duplicate
This solution is twice as nice. See what I did there?
The Problem
The Initial Attempts
This problem is seriously so simple. It’s really a morale-booster, after all these linked lists and binary trees! My whiteboard code comes together in under five minutes and passes muster:
/**
* @param {number[]} nums
* @return {boolean}
*/
var containsDuplicate = function(nums) {
nums.sort();
for(i=0; i < nums.length -1; i++){
if(nums[i] == nums[i+1]) return true;
}
return false;
};But it’s not enough. I know there’s another way to solve this problem: hashmap time! Will it run faster? Use less memory? I plug it in and give it a whirl.
The (Second!) Solution
var containsDuplicate = function(nums) {
let values = new Map();
for(i=0; i < nums.length; i++){
if(values.has(nums[i])){
return true
} else values.set(nums[i], i)
}
return false;
};The answer to my question is: it uses the exact same amount of memory and runs about 1/3 faster.
A twist: I apparently solved this using a Set() back in June. Whaaat! I vaguely remember looking up what a set was, but I have no idea what prompted that. Clearly I didn’t retain that information. (Although, if I was looking up how to solve this problem back in June and can now do it two different ways with my eyes closed in under 5 minutes, maybe that’s a sign of how far I’ve come in just a month.)
What I Learned
- Mostly this: you’ve got an array that needs manipulated? I’m your gal.
- Sets are a thing, who knew?
Cool beans. The end of Week 2 means I’m officially all done with the easy stuff. Now onto medium questions, eep. Also — finishing question 25 means I’m 1/3 of the way through this! Not bad! At least, not yet…
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