//

// 189.swift

// LeetCode

//

// Created by Lex on 12/30/15.

// Copyright © 2015 Lex Tang. All rights reserved.

//

/*

Rotate an array of n elements to the right by k steps.

For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4].

Note:

Try to come up as many solutions as you can, there are at least 3 different ways to solve this problem.

Hint:

Could you do it in-place with O(1) extra space?

Related problem: Reverse Words in a String II

*/

import Foundation

import XCTest

extension Array {

mutating func rotate(_ k: Int) {

let start = self.count - k

if start < 1 {

return

}

var extra = Array<Element>(self[start..<(start + k)])

extra.append(contentsOf: self[0..<(count - k)])

self = extra

}

}

class RotateArray: XCTestCase {

func testRotateArray() {

var a = [1, 2, 3, 4, 5, 6, 7]

a.rotate(3)

XCTAssertEqual(a, [5, 6, 7, 1, 2, 3, 4])

a = [1, 2, 3, 4, 5, 6, 7]

a.rotate(1)

XCTAssertEqual(a, [7, 1, 2, 3, 4, 5, 6])

a = [1]

a.rotate(1)

XCTAssertEqual(a, [1])

a = []

a.rotate(1)

XCTAssertEqual(a, [])

a = [1, 2, 3]

a.rotate(3)

XCTAssertEqual(a, [1, 2, 3])

}

}