Added Sparse Search to Strings

String/Sparse Search/sparsesearch.cpp

@@ -0,0 +1,73 @@
+// C++ program to implement binary search
+// in a sparse array.
+#include <bits/stdc++.h>
+using namespace std;
+
+/* Binary Search in an array with blanks */
+int binarySearch(string *arr, int low, int high, string x)
+{
+  if (low > high)
+    return -1;
+
+  int mid = (low + high) / 2;
+
+  /*Modified Part*/
+  if (arr[mid] == "")
+  {
+    int left = mid - 1;
+    int right = mid + 1;
+
+    /*Search for both side for a non empty string*/
+    while (1)
+    {
+
+      /* No non-empty string on both sides */
+      if (left < low && right > high)
+        return -1;
+
+      if (left >= low && arr[left] != "")
+      {
+        mid = left;
+        break;
+      }
+
+      else if (right <= high && arr[right] != "")
+      {
+        mid = right;
+        break;
+      }
+
+      left--;
+      right++;
+    }
+  }
+
+  /* Normal Binary Search */
+  if (arr[mid] == x)
+    return mid;
+  else if (arr[mid] > x)
+    return binarySearch(arr, low, mid - 1, x);
+  else
+    return binarySearch(arr, mid + 1, high, x);
+}
+
+int sparseSearch(string arr[], string x, int n)
+{
+  return binarySearch(arr, 0, n - 1, x);
+}
+
+int main()
+{
+  ios_base::sync_with_stdio(false);
+
+  string arr[] = {"for", "geeks", "", "", "", "", "ide",
+                  "practice", "", "", "", "quiz"};
+  string x = "geeks";
+  int n = sizeof(arr) / sizeof(arr[0]);
+  int index = sparseSearch(arr, x, n);
+  if (index != -1)
+    cout << x << " found at index " << index << "\n";
+  else
+    cout << x << " not found\n";
+  return 0;
+}