text: Function for push down operation on the segment tree
code: void pushDown ( vector < int > & sum , vector < int > & add , int rt , int ln , int rn ) { if ( add [ rt ] ) { add [ rt << 1 ] += add [ rt ] ; add [ rt << 1 1 ] += add [ rt ] ; sum [ rt << 1 ] += add [ rt ] * ln ; sum [ rt << 1 1 ] += add [ rt ] * rn ; add [ rt ] = 0 ; } }