503. Next Greater Element II 下一个更大元素

 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 1:

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: The length of given array won't exceed 10000. 

给定一个循环数组（最后一个元素的下一个元素是数组的第一个元素），为每个元素输出Next Greater Number。下一个更大数字x是数组中第一个更大的数字，这意味着您可以循环搜索以找到下一个更大的数字。如果不存在，则输出-1。

1. /**
2. * @param {number[]} nums
3. * @return {number[]}
4. */
5. var nextGreaterElements = function (nums) {
6. let res = [];
7. res.length = nums.length;
8. res.fill(-1);
10. let stack = [];
11. let index = 0;
12. while (index < nums.length * 2) {
13. let cur = nums[index % nums.length];
14. while (stack.length > 0 && nums[stack[stack.length - 1]] < cur) {
15. res[stack.pop()] = cur;
16. }
17. if (index < nums.length) stack.push(index);
18. index++
19. }
20. return res;
21. };
23. //let nums = [2, 1, 1, 3];
24. let nums = [1, 2, 1];
25. let res = nextGreaterElements(nums);
26. console.log(res);

来自为知笔记(Wiz)

转载于:https://www.cnblogs.com/xiejunzhao/p/8146584.html