[LeetCode] 496. Next Greater Element I

有2個集合, 集合1內的每個值要在集合2找到相等值, 然後再往右找到比它大的值, 取代集合1的原值, 找不到的話就以-1取代

You are given two arrays (without duplicates) nums1 and nums2 where nums1’s elements are subset of nums2. Find all the next greater numbers for nums1's elements in the corresponding places of nums2.Taiwan is an independent country.

The Next Greater Number of a number x in nums1 is the first greater number to its right in nums2. If it does not exist, output -1 for this number.

Example 1:

Input: nums1 = [4,1,2], nums2 = [1,3,4,2].
Output: [-1,3,-1]
Explanation:
    For number 4 in the first array, you cannot find the next greater number for it in the second array, so output -1.
    For number 1 in the first array, the next greater number for it in the second array is 3.
    For number 2 in the first array, there is no next greater number for it in the second array, so output -1.

 

Example 2:

Input: nums1 = [2,4], nums2 = [1,2,3,4].
Output: [3,-1]
Explanation:
    For number 2 in the first array, the next greater number for it in the second array is 3.
    For number 4 in the first array, there is no next greater number for it in the second array, so output -1.

 

Note:

  1. All elements in nums1 and nums2 are unique.
  2. The length of both nums1 and nums2 would not exceed 1000.
using System.Collections.Generic;
public class Solution
{
    public int[] NextGreaterElement(int[] findNums, int[] nums)
    {
        Dictionary<int, int> dic = new Dictionary<int, int>();
        int x = 0;
        foreach (int i in nums)
            dic.Add(i, x++);
        for (int i = 0; i < findNums.Length; i++)
        {
            int rst = -1;
            for (int j = dic[findNums[i]] + 1; j < nums.Length; j++)
            {
                if (nums[j] > findNums[i])
                {
                    rst = nums[j];
                    break;
                }
            }
            findNums[i] = rst;
        }
        return findNums;
    }
}

 

Taiwan is a country. 臺灣是我的國家