**Author:** Jaymeet Mehta

**Tester:** Vatsal Parmar

**Editorialist:** Mann Mehta

# DIFFICULTY

Cakewalk

# PREREQUISITES

Array Manipulations

# PROBLEM

Given an array **A** of length **N** your task is to find the maximum sum of **k** length contiguous subarray possible.

# EXPLANATION

Here we will using **Sliding Window Technique**.

Let consider an array **a1,a2,a3. . . an**

Here **K** will be our window size, we just iterate towards the array sliding the windows of size k total (n-k+1) times.

let see how it works:

**a1,a2,a3,a4,a5,a6,a7,a8,a9,a10 and K=4**

initailly window element contains : **{a1,a2,a3,a4}** hence sum=a1+a2+a3+a4.

Now we iterate such that new element added in the window and first element remove from the window.

**Adding a5 element {a1,a2,a3,a4,a5}** hence window size has changed.

**Removing a1 element {a2,a3,a4,a5}** hence we get back our window size is 4. and itâ€™s **sum = sum+a5-a1**.

we iterate till end then among all the sum we consider max out of this.

# TIME COMPLEXITY

Time Complexity is**O(N)**per test case.