create right son of root
int set_right ( char key , int parent ) { if ( tree [ parent ] == ' \0' ) cout << " Can ' set child at " << ( parent * 2 ) + 2 << " ▁ , ▁ no ▁ parent ▁ found " ; else tree [ ( parent * 2 ) + 2 ] = key ; return 0 ; }