Create Suffix.cpp

Cpp/Suffix.cpp

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+// Naive algorithm for building suffix array of a given text
+#include <iostream>
+#include <cstring>
+#include <algorithm>
+using namespace std;
+
+// Structure to store information of a suffix
+struct suffix
+{
+	int index;
+	char *suff;
+};
+
+// A comparison function used by sort() to compare two suffixes
+int cmp(struct suffix a, struct suffix b)
+{
+	return strcmp(a.suff, b.suff) < 0? 1 : 0;
+}
+
+// This is the main function that takes a string 'txt' of size n as an
+// argument, builds and return the suffix array for the given string
+int *buildSuffixArray(char *txt, int n)
+{
+	// A structure to store suffixes and their indexes
+	struct suffix suffixes[n];
+
+	// Store suffixes and their indexes in an array of structures.
+	// The structure is needed to sort the suffixes alphabetically
+	// and maintain their old indexes while sorting
+	for (int i = 0; i < n; i++)
+	{
+		suffixes[i].index = i;
+		suffixes[i].suff = (txt+i);
+	}
+
+	// Sort the suffixes using the comparison function
+	// defined above.
+	sort(suffixes, suffixes+n, cmp);
+
+	// Store indexes of all sorted suffixes in the suffix array
+	int *suffixArr = new int[n];
+	for (int i = 0; i < n; i++)
+		suffixArr[i] = suffixes[i].index;
+
+	// Return the suffix array
+	return suffixArr;
+}
+
+// A utility function to print an array of given size
+void printArr(int arr[], int n)
+{
+	for(int i = 0; i < n; i++)
+		cout << arr[i] << " ";
+	cout << endl;
+}
+
+// Driver program to test above functions
+int main()
+{
+	char txt[] = "banana";
+	int n = strlen(txt);
+	int *suffixArr = buildSuffixArray(txt, n);
+	cout << "Following is suffix array for " << txt << endl;
+	printArr(suffixArr, n);
+	return 0;
+}