#include using namespace std; class Solution{ public: int numberOfBeams(vector & bank){ int len = bank.size(); vector null_bank; for(string row_plan: bank){ bool flag = 1; for(char ch: row_plan){ if(ch == '1'){ flag = 0; break; } } if(!flag) null_bank.push_back(row_plan); } long long ans = 0; int last = 0; for(string row_plan: null_bank){ int num = 0; for(char ch : row_plan){ if(ch == '1') num++; } ans += num*last; last = num; } return ans; } }; int main(){ Solution sol; vector ex1 = {"011001","000000","010100","001000"}; cout<<"ex1"< ex2 = {"000","000","000"}; cout<<"ex2"<