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Difficulty: Easy
Contributors: Admin
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.
[show hint]
Hint:Could you do it in-place with O(1) extra space?
Related problem: Reverse Words in a String II
Credits:Special thanks to @Freezen for adding this problem and creating all test cases.
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(M) Rotate List (M) Reverse Words in a String II
/*
let a= [1,2,3,4,5,6,7]
k = 3.
we have to first reverse the whole array by swapping first element with the last one and so on..
you will get[7,6,5,4,3,2,1]
reverse the elements from 0 to k-1
reverse the elements 7,6,5
you will get [5,6,7,4,3,2,1]
reverse the elements from k to n-1
reverse the elements 4,3,2,1
you will get[5,6,7,1,2,3,4]
*/
public void reverse(int[] nums, int start, int end) {
while (start < end) {
int temp = nums[start];
nums[start] = nums[end];
nums[end] = temp;
start++;
end--;
}
}
public void rotate(int[] nums, int k) {
k %= nums.length;
reverse(nums, 0, nums.length - 1);
reverse(nums, 0, k - 1);
reverse(nums, k, nums.length - 1);
}
