day 41: 33-search-in-rotated-sorted-array

33-search-in-rotated-sorted-array/driver.cpp

@@ -0,0 +1,11 @@
+#include "soln.hpp"
+
+int main()
+{
+	vector<int> nums{4, 5, 6, 7, 0, 1, 2};
+	int target = 0;
+	int answer = 4;
+	Solution soln;
+	cout << "Searched rotated sorted array correctly? " << soln.test(nums, target, answer) << endl;
+	return 0;
+}

33-search-in-rotated-sorted-array/soln.cpp

@@ -0,0 +1,91 @@
+#include "soln.hpp"
+
+int Solution::search(vector<int> &nums, int target)
+{
+	if (nums.size() == 1)
+	{
+		return nums[0] == target ? 0 : -1;
+	}
+	else if (nums.size() == 2)
+	{
+		return nums[0] == target ? 0 : nums[1] == target ? 1
+														 : -1;
+	}
+	int low = 0, high = nums.size() - 1, mid, pivot = -1;
+	// check 0 rotation edge cases
+	// if so, perform binary search right here
+	if (nums[low] < nums[high])
+	{
+		while (low < high)
+		{
+			mid = (low + high) / 2;
+			if (nums[mid] == target)
+			{
+				return mid;
+			}
+			else if (nums[mid] < target)
+			{
+				low = mid + 1;
+			}
+			else
+			{
+				high = mid - 1;
+			}
+		}
+		return nums[low] == target ? low : -1;
+	}
+	// find pivot
+	low = 0, high = nums.size() - 1;
+	while (low < high)
+	{
+		mid = (low + high) / 2;
+		if (
+			(mid == 0 && nums[mid] > nums[mid + 1]) ||
+			(mid != 0 && nums[mid] >= nums[mid - 1] && nums[mid] > nums[mid + 1]))
+		{
+			pivot = mid;
+			break;
+		}
+		if (nums[mid] < nums[low])
+		{
+			high = mid;
+		}
+		else
+		{
+			low = mid + 1;
+		}
+	}
+	// find half it should be in
+	low = 0, high = nums.size() - 1;
+	if (target < nums[low])
+	{
+		low = pivot + 1;
+	}
+	else
+	{
+		high = pivot;
+	}
+	// binary search that half
+	while (low < high)
+	{
+		mid = (low + high) / 2;
+		if (nums[mid] == target)
+		{
+			return mid;
+		}
+		else if (nums[mid] < target)
+		{
+			low = mid + 1;
+		}
+		else
+		{
+			high = mid - 1;
+		}
+	}
+	return nums[low] == target ? low : -1;
+}
+
+bool Solution::test(vector<int> &nums, int target, int answer)
+{
+	return search(nums, target) == answer;
+}

33-search-in-rotated-sorted-array/soln.hpp

@@ -0,0 +1,8 @@
+#include <bits/stdc++.h>
+using namespace std;
+class Solution
+{
+public:
+	int search(vector<int> &nums, int target);
+	bool test(vector<int> &nums, int target, int answer);
+};