Given a circular array (the next element of the last element is the first element of the array), print the Next Greater Number for every element. The Next Greater Number of a number x is the first greater number to its traversing-order next in the array, which means you could search circularly to find its next greater number. If it doesn't exist, output -1 for this number.
Example
Input:
[1,2,1]
Output:
[2,-1,2]
Explanation:
The first 1's next greater number is 2;
The number 2 can't find next greater number;
The second 1's next greater number needs to search circularly, which is also 2
Note
环形版本,就是在两倍长度的数组上重复之前那题
Code
class Solution {
public int[] nextGreaterElements(int[] nums) {
int[] res = new int[nums.length];
Stack<Integer> stack = new Stack<>();
Arrays.fill(res, -1);
int len = nums.length;
for (int i = 0; i < 2 * len; i++) {
int num = nums[i % len];
while (!stack.isEmpty() && nums[stack.peek()] < num) {
res[stack.pop()] = num;
}
if (i < len) {
stack.push(i);
}
}
return res;
}
}