How I can start learning algorithms for ICPC to solve problems on codeforces?

there are lot many platforms out there, first thing stick to one and practice a lot n lot hackerearth is having great tutorial series under 'code monk'. hackerrank is good for beginners it has good classification of different problem categories. topcoder n codeforces have some of the world's best competitive coders refer there blogs and codes. there are lot many others like spoj, uva, codechef etc but for starting up I would recommend hackerrank. in terms of books 'introduction to algorithm' is highly recommended among others. for video tutorials u can use MITs open course of introduction to algorithm, from YouTube or MIT official site.