Sliding_Window

#include<bits/stdc++.h>
using namespace std;

int max_klength_subarray_sum(vector<int>& v, int &n, int &k) {
	int ans = INT_MIN, tempsum = 0, s = 0;
	for (int i = 0; i < n; i++) {
		tempsum += v[i];//include this element
		if ((i - s + 1) == k) {//checking the window size
			ans = max(ans, tempsum);
			tempsum -= v[s];
			s++;
		}
	}
	return ans;
}



vector<int> count_range_max_klength_subarray_sum(vector<int>& v, int &n, int&k) {
	int prevsum = -1, countans = 0, tempsum = 0, s = 0;
	pair<int, int> ans;
	for (int i = 0; i < n; i++) {
		tempsum += v[i];//include this element
		if ((i - s + 1) == k) {//checking the window size
			if (tempsum > prevsum) {
				prevsum = tempsum;
				countans = 1;
				ans.first = s, ans.second = i;
			}
			else if (tempsum == prevsum) {
				// ans.first = s, ans.second = i;
				countans++;
			}
			//tempsum-> sum of this window
			tempsum -= v[s];
			s++;
		}
	}
	return {countans, ans.first, ans.second};
}


pair<int, int> range_max_klength_subrray_sum(vector<int> &v, int &n, int &k) {/// nearer to end
	int prevsum = -1, tempsum = 0, s = 0;
	pair<int, int> ans;
	for (int i = 0; i < n; i++) {
		tempsum += v[i];
		if ((i - s + 1) == k) {
			//tempsum -> ans of this window
			if (tempsum >= prevsum) {
				prevsum = tempsum;
				ans.first = s, ans.second = i;
			}
			tempsum -= v[s];
			s++;
		}
	}
	return ans;
}



pair<int, int> range_max_klength_subrray_sum_nearer_to_start(vector<int> &v, int &n, int &k) {
	int prevsum = -1, tempsum = 0, s = 0;
	pair<int, int> ans;
	for (int i = 0; i < n; i++) {
		tempsum += v[i];
		if ((i - s + 1) == k) {
			//tempsum -> ans of this window
			if (tempsum > prevsum) {
				prevsum = tempsum;
				ans.first = s, ans.second = i;
			}
			tempsum -= v[s];
			s++;
		}
	}
	return ans;
}




int main() {
	//given an n length array and k, you eed to find the max subarray sum of length k.

	int n, k; cin >> n >> k;
	vector<int> v(n);
	for (int i = 0; i < n; i++) cin >> v[i];

	cout << max_klength_subarray_sum(v, n, k);

	vector<int> ans = count_range_max_klength_subarray_sum(v, n, k);




	return 0;

	//follow-up questions
	/*
	 1.>find number of windows having maximum sum--> done
	 2.>find the range of window having maxium sum.--> done
	 3.>find the range of window having maximum sum, but it can be as nearer to the start.--> done
	 4.>find the range of window having maximum sum, but it can be as nearer to the end.-->
	*/
}