Jump Search

jump-search.cpp

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+// Jump Search
+
+// Includes
+#include <bits/stdc++.h>
+
+// Function prototyping
+int search(int arr[], int n, int x);
+int linearSearch(int arr[], int l, int n, int x);
+
+// Main function
+int main() {
+	int arr[] = {3,4,5,6,7};
+	int n = sizeof(arr)/sizeof(arr[0]);
+	int x = 7;
+	int result = search(arr, n, x);
+	std::cout << result;
+	return 0;
+}
+
+// Jump search function
+// optimal step is square root of n
+// jumps everytime with step and checks if the value at step
+// is less than the element to be found
+// if it greater the block between prev and step is finally searched
+// using linear search but if element to be found is not in the array
+// -1 is returned
+// in linear search if element is found index is returned otherwise
+// -1 is returned
+int search(int arr[], int n, int x) {
+	int index = -1, result = 0;
+	int step = sqrt(n);
+
+	int prev = 0;
+
+	while(arr[std::min(step, n) - 1] < x) {
+		prev = step;
+		step += sqrt(n);
+		if(prev >= n) {
+			return index;
+		}
+	}
+
+	result = linearSearch(arr, prev, std::min(step, n), x);
+
+	return result;
+}
+
+
+// Linear search from linear-search.cpp with some modification
+int linearSearch(int arr[], int l, int n, int x) {
+	int index = -1, i = 0;
+	for(i=l;i<n;i++) {
+		if(arr[i] == x) {
+			index = i+1;
+			return index;
+		}
+	}
+	return index;
+}