Problem Description
Given an Array, rotate it k times
Example
Array: 1 2 3 4 5 6 7 8 9
k: 3
Output: 7 8 9 1 2 3 4 5 6
Solution
Array: 1 2 3 4 5 6 7 8 9
k: 3
In the output array, we can see that the last k elements will appear first, and then the rest of the elements will appear. So, step 1: reverse the array to get [9 8 7 6 5 4 3 2 1] The, use the “reverse an array in the given range code” to reverse the first 3 elements. Do the same for remaining elements. This will give us the final answer.
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Since k can be greater than the array length, we will need to use: k = k%arr.length |
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class Solution {
public void rotate(int[] nums, int k) {
int n = nums.length;
k = k%n;
reverseRange(nums, 0, n-1);
reverseRange(nums, 0, k-1);
reverseRange(nums, k, n-1);
}
public void reverseRange(int[] nums, int start, int end){
int i=start;
int j=end;
while(i<j){
swap(nums, i, j);
i++;
j--;
}
}
public void swap(int[] nums, int i, int j){
int temp = nums[i];
nums[i] = nums[j];
nums[j] = temp;
}
}