added some search algorithms

src/algorithms/searching/exponential_search.h

@@ -0,0 +1,31 @@
+#ifndef EXPONENTIAL_SEARCH_H
+#define EXPONENTIAL_SEARCH_H
+
+#ifdef __cplusplus
+#include "binary_search.h"
+#include <iostream>
+#endif
+
+template <typename T> int64_t exponential_search(std::vector<T> arr, T key) {
+  if (arr[0] == key) {
+    return true;
+  }
+  int64_t i = 1, n = arr.size();
+  while (i < n && arr[i] < key) {
+    i *= 2;
+  }
+  int64_t lo = i / 2, hi = std::min(i, n - 1);
+  while (lo <= hi) {
+    int64_t mid = (lo + hi) / 2;
+    if (arr[mid] == key) {
+      return mid;
+    } else if (arr[mid] < key) {
+      lo = mid + 1;
+    } else {
+      hi = mid - 1;
+    }
+  }
+  return -1;
+}
+
+#endif

src/algorithms/searching/linear_search.h

@@ -0,0 +1,17 @@
+#ifndef LINEAR_SEARCH_H
+#define LINEAR_SEARCH_H
+
+#ifdef __cplusplus
+#include <iostream>
+#endif
+
+template <typename T> bool linear_search(std::vector<T> arr, T key) {
+  for (T &x : arr) {
+    if (x == key) {
+      return true;
+    }
+  }
+  return false;
+}
+
+#endif

tests/algorithms/searching/exponential_search.cc

@@ -0,0 +1,10 @@
+#define CATCH_CONFIG_MAIN
+#include "../../../src/algorithms/searching/exponential_search.h"
+#include "../../catch2/catch.hpp"
+
+TEST_CASE("testing exponential search") {
+  std::vector<int> v = {1, 6, 43, 0, 9, 20, 60};
+  REQUIRE(exponential_search(v, 6) == 1);
+  REQUIRE(exponential_search(v, 60) == 6);
+  REQUIRE(exponential_search(v, -10) == -1);
+}

tests/algorithms/searching/linear_search.cc

@@ -0,0 +1,9 @@
+#define CATCH_CONFIG_MAIN
+#include "../../../src/algorithms/searching/linear_search.h"
+#include "../../catch2/catch.hpp"
+
+TEST_CASE("testing linear search") {
+  std::vector<int> v = {1, 5, 3, 1, 2, 3, -41, -20};
+  REQUIRE(linear_search(v, 5) == true);
+  REQUIRE(linear_search(v, -40) == false);
+}