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Longest Common Subsequence.cpp

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+//  ---------------- OUTPUT -----------------------
+// Enter the 1st string
+// AGGTAB
+// Enter the 2nd string
+// GXTXAYB
+// The longest common subsequence is : GTAB
+// Length of LCS is 4
+//  ------------------------------------------------
+
+#include <bits/stdc++.h>
+using namespace std;
+
+int max(int a, int b)
+{
+    return (a > b) ? a : b;
+}
+
+int LCS(char *X, char *Y, int m, int n)
+{
+    int L[m + 1][n + 1];
+    int i, j;
+
+    for (i = 0; i <= m; i++)
+    {
+        for (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';
+
+    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 << "\n";
+
+    return L[m][n];
+}
+
+int main()
+{
+
+    char X[100];
+    char Y[100];
+
+    cout << "Enter the 1st string" << endl;
+    gets(X);
+    cout << "Enter the 2nd string" << endl;
+    gets(Y);
+
+    int m = strlen(X);
+    int n = strlen(Y);
+
+    cout << "The longest common subsequence is : ";
+    int length = LCS(X, Y, m, n);
+    cout << "Length of LCS is "
+         << length;
+
+    return 0;
+}