Create Longest_non-decreasing_subsequence.c

Author: santhosh-programmer

Dynamic-Programming/Longest_non-decreasing_subsequence.c

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+// Problem statement:
+
+// Find the length of the Longest Non-decreasing Subsequence in a given Sequence.
+
+// Eg:
+
+// Input:9
+
+// Sequence:[-1,3,4,5,2,2,2,2,3]
+
+// the subsequence is [-1,2,2,2,2,3]
+
+// Output:6
+
+
+
+// NOTE: This code is not based on Dynamic programming, it's just normal execution.
+#include<stdio.h>
+int find(int n,int a[])
+{
+    int ans=0;
+    {
+        for(int i=0;i<n;i++)
+        {
+            if(ans>n-i)
+            return ans;
+            else
+            {
+                int l=i,r=n-1,t=1;
+                while(l<r)
+                {
+                    
+                    if(a[l]<=a[r] && (l==i || a[l]>=a[l-1]) )
+                    {
+                        if(a[r]>=a[r-1])                     
+                        r--;
+                        else
+                        l++;
+                        t++;
+                    }
+                    else if(a[l+1]>=a[l])
+                    {
+                        l++;
+                        r++;
+                    }
+                    else
+                    break;
+                }
+                if(ans<t)
+                ans=t;
+            }
+        }
+        return ans;
+    }
+}
+int main()
+{
+    int n;
+    scanf("%d",&n);
+    int a[n];
+    for(int i=0;i<n;i++)
+    scanf("%d",&a[i]);
+    printf("%d",find(n,a));
+}