Create longest_common_prefix

longest_common_prefix

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+// A C++ Program to find the longest common prefix 
+#include<bits/stdc++.h> 
+using namespace std; 
+
+// A Utility Function to find the common prefix between 
+// strings- str1 and str2 
+string commonPrefixUtil(string str1, string str2) 
+{ 
+	string result; 
+	int n1 = str1.length(), n2 = str2.length(); 
+
+	for (int i=0, j=0; i<=n1-1&&j<=n2-1; i++,j++) 
+	{ 
+		if (str1[i] != str2[j]) 
+			break; 
+		result.push_back(str1[i]); 
+	} 
+	return (result); 
+} 
+
+// A Divide and Conquer based function to find the 
+// longest common prefix. This is similar to the 
+// merge sort technique 
+string commonPrefix(string arr[], int low, int high) 
+{ 
+	if (low == high) 
+		return (arr[low]); 
+
+	if (high > low) 
+	{ 
+		// Same as (low + high)/2, but avoids overflow for 
+		// large low and high 
+		int mid = low + (high - low) / 2; 
+
+		string str1 = commonPrefix(arr, low, mid); 
+		string str2 = commonPrefix(arr, mid+1, high); 
+
+		return (commonPrefixUtil(str1, str2)); 
+	} 
+} 
+
+// Driver program to test above function 
+int main() 
+{ 
+	string arr[] = {"geeksforgeeks", "geeks", 
+					"geek", "geezer"}; 
+	int n = sizeof (arr) / sizeof (arr[0]); 
+
+	string ans = commonPrefix(arr, 0, n-1); 
+
+	if (ans.length()) 
+		cout << "The longest common prefix is "
+			<< ans; 
+	else
+		cout << "There is no common prefix"; 
+	return (0); 
+}