diff --git a/challenge-21/submissions/akolpakov-somehash/solution-template.go b/challenge-21/submissions/akolpakov-somehash/solution-template.go new file mode 100644 index 00000000..dae73970 --- /dev/null +++ b/challenge-21/submissions/akolpakov-somehash/solution-template.go @@ -0,0 +1,74 @@ +package main + +import ( + "fmt" +) + +func main() { + // Example sorted array for testing + arr := []int{1, 3, 5, 7, 9, 11, 13, 15, 17, 19} + + // Test binary search + target := 7 + index := BinarySearch(arr, target) + fmt.Printf("BinarySearch: %d found at index %d\n", target, index) + + // Test recursive binary search + recursiveIndex := BinarySearchRecursive(arr, target, 0, len(arr)-1) + fmt.Printf("BinarySearchRecursive: %d found at index %d\n", target, recursiveIndex) + + // Test find insert position + insertTarget := 8 + insertPos := FindInsertPosition(arr, insertTarget) + fmt.Printf("FindInsertPosition: %d should be inserted at index %d\n", insertTarget, insertPos) +} + +// BinarySearch performs a standard binary search to find the target in the sorted array. +// Returns the index of the target if found, or -1 if not found. +func BinarySearch(arr []int, target int) int { + l, r := 0, len(arr)-1 + for l <= r { + mid := l + (r-l)/2 + if arr[mid] == target { + return mid + } + if arr[mid] < target { + l = mid + 1 + } else { + r = mid - 1 + } + } + return -1 +} + + +// BinarySearchRecursive performs binary search using recursion. +// Returns the index of the target if found, or -1 if not found. +func BinarySearchRecursive(arr []int, target int, left int, right int) int { + if left > right { + return -1 + } + mid := left + (right-left)/2 + if arr[mid] == target { + return mid + } + if arr[mid] < target { + return BinarySearchRecursive(arr, target, mid+1, right) + } + return BinarySearchRecursive(arr, target, left, mid-1) +} + +// FindInsertPosition returns the index where the target should be inserted +// to maintain the sorted order of the array. +func FindInsertPosition(arr []int, target int) int { + l, r := 0, len(arr) // r is exclusive + for l < r { + mid := l + (r-l)/2 + if arr[mid] < target { + l = mid + 1 + } else { + r = mid + } + } + return l +}