I was solving "Digit sum" problem of Atcoder DP contest. I am just curious why my two solutions have such a vast difference in their execution time.
My First solution which took more than 2000ms (https://atcoder.jp/contests/dp/submissions/24396061) 
My Second solution which took less than 200ms (used global variables) (https://atcoder.jp/contests/dp/submissions/24396078) 
Just adding some more parameters to a function completely changed the time complexity, strange isn't it?
Auto comment: topic has been updated by Kmare (previous revision, new revision, compare).
Cause you're not passing the string by reference in the first solution. In state function, change "string s" to "string& s" and you'll see a similar execution time
Got it!! Thanks
Everytime a new copy of the string gets created since you pass by value, do pass by reference, I think it will run in similar time.
Thank you!!