leaf
if ( ss == se ) { st [ i ] = ss ; return ; } int mid = ( ss + se ) >> 1 ; SegmentTreeConstruction ( ss , mid , left ) ; SegmentTreeConstruction ( mid + 1 , se , right ) ; if ( l [ st [ left ] ] < l [ st [ right ] ] ) st [ i ] = st [ left ] ; else st [ i ] = st [ right ] ; }