Create SentinelSearch.cpp

SentinelSearch.cpp

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+#include <iostream>
+#include <vector>
+using namespace std;
+
+// Function to search x in the given vector
+int sentinelSearch(vector<int>& arr, int key) {
+
+    // Last element of the vector
+    int last = arr.back();
+
+    // Element to be searched is placed at the last index
+    arr.back() = key;
+    int i = 0;
+    while (arr[i] != key)
+        i++;
+
+    // Put the last element back
+    arr.back() = last;
+
+    // Return the index if found, otherwise return -1
+    if ((i < arr.size() - 1) || (arr.back() == key))
+        return i;
+    else
+        return -1;
+}
+
+int main() {
+    vector<int> arr = { 10, 20, 180, 30, 60, 50, 110, 100, 70 };
+    int key = 180;
+    int result = sentinelSearch(arr, key);
+    if (result != -1)
+        cout << key << " is present at index " << result;
+    else
+        cout << "Element not found";
+
+    return 0;
+}