Segment Tree Practice 3
View as PDFGiven an array  of size 
, support the 
 of the following operations:
- Find the maximum prefix sum of the subarray from index 
to index
. That is, find the maximum sum of a subarray starting at
and ending in the range
.
 - Update the element at index 
to value
.
 
Constraints
Input Specification
The first line contains  integers 
 and 
.
The second line contains  integers 
, the initial elements of 
.
The next  lines are one of two forms:
P l rrepresenting the first operation.U i xrepresenting the second operation.
Output Specification
For each type  operation output one integer on its own line, the answer to that query.
Sample Input
7 5
-1 3 2 -6 5 -6 7
P 2 6
P 5 7
U 4 -3
P 2 6
P 1 1
Sample Output
5
6
7
-1
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