Create Ternary_search.c

C/Ternary_search.c

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+// C program to illustrate
+// recursive approach to ternary search
+
+#include <stdio.h>
+
+// Function to perform Ternary Search
+int ternarySearch(int l, int r, int key, int ar[])
+{
+ if (r >= l) {
+
+ // Find the mid1 and mid2
+ int mid1 = l + (r - l) / 3;
+ int mid2 = r - (r - l) / 3;
+
+ // Check if key is present at any mid
+ if (ar[mid1] == key) {
+ return mid1;
+ }
+ if (ar[mid2] == key) {
+ return mid2;
+ }
+
+ // Since key is not present at mid,
+ // check in which region it is present
+ // then repeat the Search operation
+ // in that region
+
+ if (key < ar[mid1]) {
+
+ // The key lies in between l and mid1
+ return ternarySearch(l, mid1 - 1, key, ar);
+ }
+ else if (key > ar[mid2]) {
+
+ // The key lies in between mid2 and r
+ return ternarySearch(mid2 + 1, r, key, ar);
+ }
+ else {
+
+ // The key lies in between mid1 and mid2
+ return ternarySearch(mid1 + 1, mid2 - 1, key, ar);
+ }
+ }
+
+ // Key not found
+ return -1;
+}
+
+// Driver code
+int main()
+{
+ int l, r, p, key;
+
+ // Get the array
+ // Sort the array if not sorted
+ int ar[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
+
+ // Starting index
+ l = 0;
+
+ // length of array
+ r = 9;
+
+ // Checking for 5
+
+ // Key to be searched in the array
+ key = 5;
+
+ // Search the key using ternarySearch
+ p = ternarySearch(l, r, key, ar);
+
+ // Print the result
+ printf("Index of %d is %d\n", key, p);
+
+ // Checking for 50
+
+ // Key to be searched in the array
+ key = 50;
+
+ // Search the key using ternarySearch
+ p = ternarySearch(l, r, key, ar);
+
+ // Print the result
+ printf("Index of %d is %d", key, p);
+}