Rolling String problem solution in python def roll(s, op): res="" for a in op: if (a[2]=='L'): for b in range(int(a[0]), int(a[1])+1): if(s[b]=='a'): s = s[:b]+'z'+s[b+1:] else: s = s[:b]+chr(ord(s[b])-1)+s[b+1:] if (a[2]=='R'): for b in range(int(a[0]), int(a[1])+1): if(s[b]=='z'): s = s[:b]+'a'+s[b+1:] else: s = s[:b]+chr(ord(s[b])+1)+s[b+1:] return s roll('abc', ['00L','22L','02R'])