Two problems were asked:

1. Give a binary tree, each node has a value. It is rooted at 1.
   let $S1(v)$ = sum of node values in the path from $1$ to $v$
   $S2(v)$ = sum of nodes values which have $v$ as ancestor.
   For each node find $|s1(v)-s2(v)|$ , return their sum;

2. Give a binary string, and two type of queries
   type 1: Change the value at $i$ to $x$
   type 2: find the longest substring in $l$ to $r$, where start and end of the substring is ${}^{\prime }{1}^{\prime }$

$x=0$ or $1$
Size of string and no of queriese are upto $10^5$

Edit: Asked in IITH for placements