Print all LCS added

Author: coderdoze

Dynamic Programming/Longest Common Subsequence/LCS_print_all.c++

@@ -0,0 +1,72 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int dp[50][50];
+//use recursion to print all possible solutions
+//set to store the possible lcs in non-repeating and in increasing order(alphabetically)
+set<string> getAllLCS(string a,string b,int n,int m)
+{
+	set<string> ans;
+
+    if(n==0 || m==0)
+    {
+    	ans.insert("");
+    	return ans;
+    }
+
+	if(a[n-1]==b[m-1])
+	{
+		set<string> tmp=getAllLCS(a,b,n-1,m-1);
+		for(string s:tmp)
+			ans.insert(s+a[n-1]);
+
+	}
+
+
+	else
+	{
+		 if(dp[n-1][m]>=dp[n][m-1])
+		 	ans=getAllLCS(a,b,n-1,m);
+
+
+		 if(dp[n][m-1]>=dp[n-1][m])
+		 {
+		 	set<string> tmp=getAllLCS(a,b,n,m-1);
+
+		 	ans.insert(tmp.begin(),tmp.end());
+		 }
+	}
+
+	return ans;
+
+
+}
+int main()
+{
+	string a,b;
+	cin>>a>>b;
+
+	int n=a.size();
+	int m=b.size();
+
+	
+
+	memset(dp,0,sizeof(dp));
+
+    //construct the lcs matrix
+	for(int i=1;i<=n;i++)
+	{
+		for(int j=1;j<=m;j++)
+		{
+			if(a[i-1]==b[j-1])
+				dp[i][j]=dp[i-1][j-1]+1;
+			else
+				dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
+		}
+	}
+
+   set<string> ans=getAllLCS(a,b,n,m);
+
+   for(auto it:ans)
+   cout<<it<<" ";	
+}