Isn't it 'Easy'?

class Solution {public:    int findPoisonedDuration(vector
     
      & ts, int d)     {        int ret = 0, s = 0, e = 0;        for(auto t : ts)        {            if(t > e)             {                ret += e - s;                s = t;            }                        e = t + d;        }        ret += e - s;                return ret;    }};