Driver code
int main ( ) { char in [ ] = { ' D ' , ' B ' , ' E ' , ' A ' , ' F ' , ' C ' } ; char pre [ ] = { ' A ' , ' B ' , ' D ' , ' E ' , ' C ' , ' F ' } ; int len = sizeof ( in ) / sizeof ( in [ 0 ] ) ; node * root = buildTree ( in , pre , 0 , len - 1 ) ;