Dynamic Range Sum Queries

Given an array of n integers, your task is to process q queries of the following types: - update the value at position k to u - what is the sum of values in range [a,b]? Input The first input line has two integers n and q: the number of values and queries. The second line has n integers x_1,x_2,\dots,x_n: the array values. Finally, there are q lines describing the queries. Each line has thre