2043. Simple Bank System
C++ class Bank { vector < long long > balance ; bool valid ( int account ) { return account > 0 && account <= balance . size (); } bool enough ( int account , long long money ) { return balance [ account - 1 ] >= money ; } public: Bank ( vector < long long >& balance ) : balance ( balance ) {} bool transfer ( int from , int to , long long money ) { if ( valid ( from ) && valid ( to ) && enough ( from , money )) { balance [ from - 1 ] -= money ; balance [ to - 1 ] += money ; return true ; } return false ; } bool deposit ( int account , long long money ) { if ( valid ( account )) { balance [ account - 1 ] += money ; return true ; } return false ; } bool withdraw ( int account...