andyttran / guide_to_algorithms Goto Github PK

hello,

• i am trying to understand the complexity of map method in js.
• can you tell me which one is better one.
• since in some of my react code I see people using map method http://jsfiddle.net/jhudson8/135oo6f8/.
• not sure when to use map method and for loop.
• I am providing two codes below.
• using this example I calculated complexity https://github.com/andyttran/guide_to_algorithms#1c-analyze-line-by-line
• and found for loop has 14 operations and map method has 9 operations.
• in the coments below I have given value one for e ch operation.
• can you tell me whether I have done it correctly

for loop

var cars =[
{'toyota' : 'corolla', 'honda' : 'civic'},
{'toyota' : 'corolla1', 'honda' : 'civic1'},
{'toyota' : 'corolla2', 'honda' : 'civic2'},
{'toyota' : 'corolla3', 'honda' : 'civic3'},
];
var names = []; //names = 1, [] = 1
for(var i=0; i< cars.length; i++) { // for = 1 , var i = 1, =0 = 1, < = 1, cars.length = 1, i++ = 1
names.push(cars[i].toyota); //names = 1, push = 1, cars[i] = 1, toyota = 1
}
console.log(names); has an array access and then a printing to the console, so thats 2 operations
total = 14

map method js

var cars =[
{'toyota' : 'corolla', 'honda' : 'civic'},
{'toyota' : 'corolla1', 'honda' : 'civic1'},
{'toyota' : 'corolla2', 'honda' : 'civic2'},
{'toyota' : 'corolla3', 'honda' : 'civic3'},
];

var mapValues = cars.map(function(animal){ //mapvalues = 1, cars = 1, map= 1, function= 1
return animal.toyota; //return = 1, animal = 1, toyota = 1
});
console.log(mapValues); // has an array access and then a printing to the console, so thats 2 operations
total = 9

The link that is provided for the cheat sheet has a typo.

In the solution to Problem Set 1 (the very last line of the README) it says:

10. 300n^5 + 15002^n + 3n // O(n^5)

However doesn't the 15002^n term dominate (similarly to how 2^n dominates n^2)?