From bee51ad30bdb409e558090868c28c10c0bae2b0f Mon Sep 17 00:00:00 2001
From: P A Y A L <60649731+blaze116@users.noreply.github.com>
Date: Thu, 7 Oct 2021 20:46:17 +0530
Subject: [PATCH] Create Maximum sum subarray of size k.cpp

---
 .../Maximum sum subarray of size k.cpp        | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 DSA/Basic-DSA-Questions/Sliding Window/Maximum sum subarray of size k.cpp

diff --git a/DSA/Basic-DSA-Questions/Sliding Window/Maximum sum subarray of size k.cpp b/DSA/Basic-DSA-Questions/Sliding Window/Maximum sum subarray of size k.cpp
new file mode 100644
index 00000000..155e8b91
--- /dev/null
+++ b/DSA/Basic-DSA-Questions/Sliding Window/Maximum sum subarray of size k.cpp	
@@ -0,0 +1,43 @@
+// This is the code for finding maximum sum of a subarray of size k using sliding
+// window approach. Time complexity: O(n)
+
+#include<bits/stdc++.h>
+using namespace std;
+#define fast              ios::sync_with_stdio(false);cin.tie(0);
+
+int findmaxsum(vector<int>& arr, int k)
+{
+    int sum=0, maxsum=INT_MIN;
+    int i=0, j=0;
+    int n= arr.size();
+
+    while(j<n)
+    {
+        sum+= arr[j];  //add element to sum
+
+        if(j-i+1 <k)   //check if window size reached
+        {
+            j++;
+        }
+        else if((j-i+1)==k)
+        {
+            maxsum= max(maxsum, sum);
+            sum-=arr[i];
+            i++;
+            j++;
+        }
+    }
+    return maxsum;
+}
+
+int main()
+{
+    fast
+    vector<int> arr{1, 4, 2, 10, 23, 3, 1, 0, 20};
+    int k=4;
+    // output will be 39
+
+    cout<<"maximum sum of a subarray of size "<<k<<" is "<< findmaxsum(arr, k);
+
+    return 0;
+}