The original link of the problem is here: https://code.google.com/codejam/contest/90101/dashboard#s=p2&a=2 In simple words we need to find how many times the string S="welcome to code jam" appears as a sub-sequence of given string S, e.g. S="welcome to code jam" T="wweellccoommee to code qps jam" I know the theory but not good at DP in practice. Would you please explain step-by-step process to solve this DP problem on example and why it works?