Merge pull request #299 from KeerthanaPravallika/KeerthanaPravallika

Added Longest Common Substring program (in cpp)

Author: smv1999

Dynamic Programming/Longest_common_substring.cpp

@@ -0,0 +1,51 @@
+/*
+  Given two strings. The task is to find the length of the longest common substring.
+*/
+
+#include<bits/stdc++.h>
+using namespace std;
+
+class Solution{
+    public:
+    
+    int longestCommonSubstr (string s1, string s2, int n, int m)
+    {
+        int len_subs[n+1][m+1];
+        int i,j,maxLength=0;
+        
+        for(i=0;i<=n;i++)
+            len_subs[i][0] = 0;             //first row
+            
+        for(i=0;i<=m;i++)
+            len_subs[0][i] = 0;             // first column
+            
+        for(i = 1;i<=n;i++)
+        {
+            for(j=1;j<=m;j++)
+            {
+                if(s1[i-1] == s2[j-1])
+                {
+                    len_subs[i][j] = 1 + len_subs[i-1][j-1];
+                    if(maxLength < len_subs[i][j])
+                        maxLength = len_subs[i][j];
+                }
+                else
+                    len_subs[i][j] = 0;
+            }
+        }
+        return maxLength;
+    }
+};
+int main()
+{
+    int t; cin >> t;
+    while (t--)
+    {
+        int n, m; cin >> n >> m;
+        string s1, s2;
+        cin >> s1 >> s2;
+        Solution ob;
+
+        cout << ob.longestCommonSubstr (s1, s2, n, m) << endl;
+    }
+}