Create lcs.cpp

Author: GarimaMahajan20

lcs.cpp

@@ -0,0 +1,66 @@
+#include <bits/stdc++.h>
+using namespace std;
+void lcs(string X, string Y, int m, int n)
+{
+    int L[m + 1][n + 1];
+
+    for (int i = 0; i <= m; i++)
+    {
+        for (int j = 0; j <= n; j++)
+        {
+            if (i == 0 || j == 0)
+            {
+                L[i][j] = 0;
+            }
+            else if (X[i - 1] == Y[j - 1])
+            {
+                L[i][j] = L[i - 1][j - 1] + 1;
+            }
+            else
+            {
+                L[i][j] = max(L[i - 1][j], L[i][j - 1]);
+            }
+        }
+    }
+
+    int index = L[m][n];
+    char lcs[index + 1];
+    lcs[index] = '\0';
+
+    int i = m, j = n;
+    while (i > 0 && j > 0)
+    {
+        if (X[i - 1] == Y[j - 1])
+        {
+            lcs[index - 1] = X[i - 1];
+            i--, j--, index--;
+        }
+        else if (L[i - 1][j] > L[i][j - 1])
+        {
+            i--;
+        }
+        else
+        {
+            j--;
+        }
+    }
+    cout << lcs << endl;
+}
+int main()
+{
+    string X, Y;
+    cin >> X >> Y;
+    int m = X.length();
+    int n = Y.length();
+    lcs(X, Y, m, n);
+    return 0;
+}
+
+/*
+Time Complexity : O(n^2)
+Space Complexity : O(n^2)
+The user is expected to enter the two string whose longest common 
+subsequence is to be found.
+Input : AGGTAB
+        GXTXAYB
+Output : GTAB