# 503. Next Greater Element II

## Description

Given a circular integer array nums (i.e., the next element of nums[nums.length - 1] is nums[0]), return the next greater number for every element in nums.

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, return -1 for this number.

Example 1:

Input: nums = [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.


Example 2:

Input: nums = [1,2,3,4,3]
Output: [2,3,4,-1,4]


Constraints:

• 1 <= nums.length <= 104
• -109 <= nums[i] <= 109

## Solutions

• class Solution {
public int[] nextGreaterElements(int[] nums) {
int n = nums.length;
int[] ans = new int[n];
Arrays.fill(ans, -1);
Deque<Integer> stk = new ArrayDeque<>();
for (int i = 0; i < (n << 1); ++i) {
while (!stk.isEmpty() && nums[stk.peek()] < nums[i % n]) {
ans[stk.pop()] = nums[i % n];
}
stk.push(i % n);
}
return ans;
}
}

• class Solution {
public:
vector<int> nextGreaterElements(vector<int>& nums) {
int n = nums.size();
vector<int> ans(n, -1);
stack<int> stk;
for (int i = 0; i < (n << 1); ++i) {
while (!stk.empty() && nums[stk.top()] < nums[i % n]) {
ans[stk.top()] = nums[i % n];
stk.pop();
}
stk.push(i % n);
}
return ans;
}
};

• class Solution:
def nextGreaterElements(self, nums: List[int]) -> List[int]:
n = len(nums)
ans = [-1] * n
stk = []
for i in range(n << 1):
while stk and nums[stk[-1]] < nums[i % n]:
ans[stk.pop()] = nums[i % n]
stk.append(i % n)
return ans


• func nextGreaterElements(nums []int) []int {
n := len(nums)
ans := make([]int, n)
for i := range ans {
ans[i] = -1
}
var stk []int
for i := 0; i < (n << 1); i++ {
for len(stk) > 0 && nums[stk[len(stk)-1]] < nums[i%n] {
ans[stk[len(stk)-1]] = nums[i%n]
stk = stk[:len(stk)-1]
}
stk = append(stk, i%n)
}
return ans
}

• function nextGreaterElements(nums: number[]): number[] {
const stack: number[] = [],
len = nums.length;
const res: number[] = new Array(len).fill(-1);
for (let i = 0; i < 2 * len - 1; i++) {
const j = i % len;
while (stack.length !== 0 && nums[stack[stack.length - 1]] < nums[j]) {
res[stack[stack.length - 1]] = nums[j];
stack.pop();
}
stack.push(j);
}
return res;
}


• /**
* @param {number[]} nums
* @return {number[]}
*/
var nextGreaterElements = function (nums) {
const n = nums.length;
let stk = [];
let ans = new Array(n).fill(-1);
for (let i = 0; i < n << 1; i++) {
const j = i % n;
while (stk.length && nums[stk[stk.length - 1]] < nums[j]) {
ans[stk.pop()] = nums[j];
}
stk.push(j);
}
return ans;
};