# Sliding Window

This concept is used when there is a requirement to use consecutive elements.

For example in the above image, the window size is 3. And with each iteration, we are moving the window by one step forward. We could perform any operation on this window, e.g., summation or multiplication of window elements.

E.g., the below implementation window stores the sum of elements.

int a[n]; // array int k;// window size int window; // stores sum of the elements in the window // Assume window is initialised with sum = (a[0] + a[i] + .. +a[k-1]) // implementation of Sliding Window for(int i=k;i<n;i++) { window -= a[i-k]; // removing leftmost element of window window += a[i]; // adding new element to window cout<<"Window sum = "<<window<<endl; }

**Bonus:**

1. Window size can be dynamic based on question requirements.

2. Helps in time complexity. Without sliding window above question time

complexity would be O(n*k)

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