diff --git a/20.LongestIncreasingSubsequence.cpp b/20.LongestIncreasingSubsequence.cpp
new file mode 100644
index 0000000..7bdcade
--- /dev/null
+++ b/20.LongestIncreasingSubsequence.cpp
@@ -0,0 +1,50 @@
+/*
+ * This program takes an array from the user and returns
+ * the longest increasing subsequence's length
+ *
+ *      Coded by: Abdurrezak Efe
+ *
+ * */
+#include <iostream>
+#include <algorithm>
+
+using namespace std;
+int d[10000][10000] = {0}; //constructing dynamic array
+
+int lis(int arr[], int n)
+{
+    int b[n];
+    for(int i=0;i<n;i++)
+        b[i] = arr[i];
+
+    sort(b,b+n);
+
+    //basically calculating the lcs of the array's original and sorted versions
+    for(int i=1;i<n+1;i++)
+    {
+        for(int j=1;j<n+1;j++)
+        {
+            if(arr[i-1] == b[j-1])
+                d[i][j] = d[i-1][j-1]+1;
+            else
+                d[i][j] = max(d[i-1][j], d[i][j-1]);
+        }
+    }
+
+    return d[n][n];
+}
+
+int main()
+{
+    //taking the array
+    int n;
+    cin >> n;
+    int arr[n];
+    for(int i=0;i<n;i++)
+        cin >> arr[i];
+
+    //printing final result
+    cout << lis(arr, n) << endl;
+
+
+}