def solution(record): li = dict() answer = [] sen = [] for i, rec in enumerate(record) : rec = rec.split() op = rec[0] id = rec[1] if op == "Enter" : name = rec[2] if id in li.keys() : if li[id] != name : idx = [i for i, x in enumerate(sen) if x[0] == id] for i in idx : sen[i][1] = name li[id] = name sen.append([id, name, 1]) elif op == 'Leave' : name = li[id] sen.append([id, name, 2]) else : na..