/* $$$ challenge $$$ ¥¥ ARRAY MANIPULATION ¥¥ >>>Theory by explicit example>> QUERYLst is a list of queries to be performed on array For any query there is a list of 3 integers First int is start index Second int is end index Third int is to be added to all indices to array from start to end index. Eg.. l=10 is the size of array initialized to all 0 QUERYLst=[[1,7,4], [2,6,3], [8,10,20], [4,9,-6], [1,4,2], [6,7,-5], [5,9,1], [1,10,1], [2,5,5], [5,8,-3]] ### index starts from 1 Arr=[0,0,0,0,0,0,0,0,0,0] Now for 4th query > 4,9,-6 Array looks like this : 0,0,0,-6,-6,-6,-6,-6,-6,0 Now perform 1st & 4th query one after another. Final array looks like this 4,4,4,-2,-2,-2,-2,-6,-6,0 Assume initial array as all 0 and length 10 as example Find the final array after doing all 10 queries in QUERYList on Array **AS EFFICIENTLY AS POSSIBLE**. ans for example : 7,15,15,9,5,-5,-8,13,16,21 **dont waste time on generating other examples.. Use mine** */ #include #include #include using namespace std; constexpr int SZ{10}; //container size using SEQ = valarray; int main() { // valarray of size SZ, each element is // initialized to 0 SEQ arr(SZ); SEQ tmp(SZ); // auxillary array // a structure of three ints // representing start, end indices and // a scalar to be added (in the order) struct Data { int s, e, a; }; constexpr Data data[]{{1, 7, 4}, {2, 6, 3}, {8, 10, 20}, {4, 9, -6}, {1, 4, 2}, {6, 7, -5}, {5, 9, 1}, {1, 10, 1}, {2, 5, 5}, {5, 8, -3}}; for (auto &&t : data) { // we have a temporary valarray of // size SZ. // slice selects a subset of // valarray, the first parameter is // staring index, next is the // number of elements to select,the // last is // stride, the gap between each // element, this is 1 here since // the // elements are continuous cells. // After selecting the subset we // assign the scalar to be added to // the subset range. // so initially // tmp = [0,0,0,0,0,0,0,0,0,0] // slice selects this subset say if // start = 4, end = 9 // index >0,1,2,3,4,5,6,7,8,9 // tmp = [0,0,0,0,0,0,0,0,0,0] // ^ ^ // assign scalar to selected range // [0,0,0,-6,-6,-6,-6,-6,-6,0] // ^ ^ tmp[slice(t.s-1,t.e-t.s+1,1)] = t.a; // arr initially is // [0,0,0,0,0,0,0,0,0] // add the temporarry array element // by element // after addition arr is // [0,0,0,-6,-6,-6,-6,-6,-6,0] arr += tmp; tmp = 0; // reset the values to 0 // for next iteration // for next iteration say start=1, // end=4 and scalar=2, the generated // tmp will be // [2,2,2,2,0,0,0,0,0,0] which will // be added to previous arr values // [0,0,0,-6,-6,-6,-6,-6,-6,0] + // [2,2,2,2,0,0,0,0,0,0] = // [2,2,2,-4,-6,-6,-6,-6,-6,0] // this continues till all elements // in dataset are processed giving // us the final array } // simple print function as lambda auto print = [=](auto &&arr) { for (auto &&v : arr) cout << v << " "; cout << '\n'; }; cout << "using std::valarray:\n"; print(arr); // reset the array for new method // arr now [0,0,0,0,0,0,0,0,0,0] arr = 0; for (auto &&t : data) { // for each element in dataset // transforms the input sequence by // applying predicate to each // element in the range pointed by // begin+off to end(orbegin+off) // it can modify the sequence // in-place or copy the result of // applying the predicate to the // element, to a new sequence // starting at the position // sepecified by 3rd parameter transform(begin(arr) + (t.s - 1), begin(arr) + t.e, begin(arr) + (t.s - 1), [=](auto v) { return v + t.a; }); } cout << "using std::transform:\n"; print(arr); }

[Challenge]Array_Manipulation.cpp