Design Pattern 12: Modified Binary Search | Problem: Bitonic Point

12_bitonic_point.cpp

@@ -0,0 +1,55 @@
+/* Problem:
+ * https://practice.geeksforgeeks.org/problems/maximum-value-in-a-bitonic-array3001/1
+ */
+
+#include <iostream>
+#include <vector>
+
+int solution(const std::vector<int> &nums) {
+  if (nums.size() == 0) {
+    return -1;
+  }
+  if (nums.size() == 1) {
+    return 0;
+  };
+  long long first = 0, last = nums.size() - 1, pi = last / 2;
+  while (true) {
+    if (pi == 0) {
+      if (nums[pi] > nums[pi + 1]) {
+        return pi;
+      } else {
+        first = pi + 1;
+        pi = ((last - first) / 2) + first;
+        continue;
+      }
+    } else if (pi == (long long)nums.size() - 1) {
+      if (nums[pi] > nums[pi - 1]) {
+        return pi;
+      } else {
+        last = pi - 1;
+        pi = ((last - first) / 2) + first;
+        continue;
+      }
+    }
+    if (nums[pi] < nums[pi - 1]) {
+      last = pi - 1;
+    } else if (nums[pi] < nums[pi + 1]) {
+      first = pi + 1;
+    } else {
+      return pi;
+    }
+    pi = ((last - first) / 2) + first;
+  }
+
+  return pi;
+}
+
+int main() {
+  std::vector<int> nums1 = {1, 15, 25, 45, 42, 21, 17, 12, 11},
+                   nums2 = {1, 45, 47, 50, 5};
+  int i1, i2;
+  i1 = solution(nums1);
+  std::cout << i1 << " : " << nums1[i1] << '\n';
+  i2 = solution(nums2);
+  std::cout << i2 << " : " << nums2[i2] << '\n';
+}

CMakeLists.txt

@@ -27,4 +27,6 @@ add_executable(10_find_the_median_of_a_number_stream 10_find_the_median_of_a_num
 
 add_executable(11_letter_case_permutation 11_letter_case_permutation.cpp)
 
-add_executable(11_permutations_in_string 11_permutations_in_string.cpp)
+add_executable(11_permutations_in_string 11_permutations_in_string.cpp)
+
+add_executable(12_bitonic_point 12_bitonic_point.cpp)