LeetCode 503. Next Greater Element II

Problem Statement

impl Solution {
    pub fn next_greater_elements(nums: Vec<i32>) -> Vec<i32> {
        let n = nums.len();
        let mut ans = vec![-1; n];
        let mut stack: Vec<usize> = vec![];

        for i in 0..2 * n {
            let num = nums[i % n];
            while !stack.is_empty() {
                let top = stack.last().unwrap().clone();
                if nums[top] >= num {
                    break;
                }
                ans[top] = num;
                stack.pop();
            }
            if i < n {
                stack.push(i);
            }
        }

        return ans;
    }
}