text: Create segment tree of size 4 * n
code: Vector < Integer > sum = new Vector < Integer > ( ) ; Vector < Integer > ad = new Vector < Integer > ( ) ; Vector < Integer > ans = new Vector < Integer > ( ) ; for ( int i = 0 ; i < ( n << 2 ) ; i ++ ) { sum . add ( 0 ) ; ad . add ( 0 ) ; }