Remove an occurrence of x and an occurrence of 2 * x
m [ A [ i ] ] = m [ A [ i ] ] - 1 ; if ( m . ContainsKey ( 2 * A [ i ] ) ) m [ 2 * A [ i ] ] = m [ 2 * A [ i ] ] - 1 ; else m . Add ( 2 * A [ i ] , m [ 2 * A [ i ] ] - 1 ) ; } } if ( count == n ) return " True " ; else return " False " ; }