This is every programmer's need at present. All the programmers know how to write code, but writing an efficient code is an art. This is the area where you improve your coding skills to make programs which runs very swiftly as well as use our memory in a stingy manner. You can find many platforms for this like hackerearth, hackerrank, codechef and so on...
Fore more on competitive coding, visit this page: Competitive coding - Wikipedia