They start off that way, so it is good for that, but that flips around in later problems... coding them is not the hard part. Many require nontrivial mathematical insight to solve in any practical time frame.
http://rosettacode.org/wiki/Rosetta_Code
As long as you just read the problem description first, and don't cheat by skipping right to the implementations.
Examples: cses.fi/problemset , codeforces.com , codechef.com , hackerrank.com (tho HR makes it harder to find the good problems every time I look).