Create lcs.cpp

Dynamic Programming/lcs.cpp

@@ -0,0 +1,52 @@
+// The longest common subsequence in C++
+
+#include <iostream>
+using namespace std;
+
+void lcsAlgo(char *S1, char *S2, int m, int n) {
+  int LCS_table[m + 1][n + 1];
+
+
+  // Building the mtrix in bottom-up way
+  for (int i = 0; i <= m; i++) {
+    for (int j = 0; j <= n; j++) {
+      if (i == 0 || j == 0)
+        LCS_table[i][j] = 0;
+      else if (S1[i - 1] == S2[j - 1])
+        LCS_table[i][j] = LCS_table[i - 1][j - 1] + 1;
+      else
+        LCS_table[i][j] = max(LCS_table[i - 1][j], LCS_table[i][j - 1]);
+    }
+  }
+
+  int index = LCS_table[m][n];
+  char lcsAlgo[index + 1];
+  lcsAlgo[index] = '\0';
+
+  int i = m, j = n;
+  while (i > 0 && j > 0) {
+    if (S1[i - 1] == S2[j - 1]) {
+      lcsAlgo[index - 1] = S1[i - 1];
+      i--;
+      j--;
+      index--;
+    }
+
+    else if (LCS_table[i - 1][j] > LCS_table[i][j - 1])
+      i--;
+    else
+      j--;
+  }
+
+  // Printing the sub sequences
+  cout << "S1 : " << S1 << "\nS2 : " << S2 << "\nLCS: " << lcsAlgo << "\n";
+}
+
+int main() {
+  char S1[] = "ACADB";
+  char S2[] = "CBDA";
+  int m = strlen(S1);
+  int n = strlen(S2);
+
+  lcsAlgo(S1, S2, m, n);
+}