added longest increasing subsequence code

Author: Tarunkmr0023

20. Dynamic Programming/Longest_increasing_subsequence.cpp

@@ -0,0 +1,41 @@
+// Longest Increasing Subsequence
+#include<iostream>
+using namespace std;
+int lis(int* a,int n)
+{
+    int* output=new int[n];
+    output[0]=1;
+    for(int i=1;i<n;i++)
+    {
+        output[i]=1;
+        for(int j=i-1;j>=0;j--)
+        {
+            if(a[j]<a[i] && output[i]<output[j]+1)
+            {
+                output[i]=output[j]+1;
+            }
+        }
+    }
+    int ans=0;
+    for(int i=0;i<n;i++)
+    {
+        if(ans<output[i])
+        {
+            ans=output[i];
+        }
+    }
+    return ans;
+    
+}
+int main()
+{
+    int size;
+    cin>>size;
+    int* arr=new int[size];
+    for(int i=0;i<size;i++)
+    {
+        cin>>arr[i];
+    }
+    cout<<lis(arr,size);
+    return 0;
+}