Create LongestCommonSubsequence.cpp

LongestCommonSubsequence.cpp

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+// Longest Common Subsequence
+
+#include<bits/stdc++.h>
+
+using namespace std;
+
+
+//recursion approach
+int solve(string s1, int i, string s2, int j)
+{
+    if(i==s1.length() || j==s2.length())return 0;
+    if(s1[i]==s2[j])
+    {
+        return 1 + solve(s1, i+1, s2, j+1);
+    }
+    else
+    {
+        return max(solve(s1, i+1, s2, j), solve(s1, i, s2, j+1));
+    }
+}
+
+
+//dp approach
+int solve2(string s1, string s2)
+{
+    int dp[s2.length()+1][s1.length()+1];
+    for(int i=0; i<=s2.length(); i++)
+    {
+        for(int j=0; j<=s1.length(); j++)
+        {
+            if(i==0 || j==0)dp[i][j]=0;
+            else if(s2[i-1]==s1[j-1]) dp[i][j]=1+dp[i-1][j-1];
+            else dp[i][j]=max(dp[i][j-1], dp[i-1][j]);
+        }
+    }
+    return dp[s2.length()][s1.length()];
+}
+
+
+int main()
+{
+    string s1, s2;
+    cin>>s1>>s2;
+    // cout<<solve(s1, 0, s2, 0)<<endl;
+    cout<<solve2(s1, s2)<<endl;
+    return 0;
+
+}