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https://github.com/TheAlgorithms/Ruby
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64 lines
2 KiB
Ruby
64 lines
2 KiB
Ruby
# You are given two integer arrays nums1 and nums2 both of unique elements, where nums1 is a subset of nums2.
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#
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# Find all the next greater numbers for nums1's elements in the corresponding places of nums2.
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#
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# 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, return -1 for this number.
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# Example 1:
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#
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# Input: nums1 = [4,1,2], nums2 = [1,3,4,2]
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# Output: [-1,3,-1]
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#
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# Explanation:
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# For number 4 in the first array, you cannot find the next greater number for it in the second array, so output -1.
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# For number 1 in the first array, the next greater number for it in the second array is 3.
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# For number 2 in the first array, there is no next greater number for it in the second array, so output -1.
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#
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# Example 2:
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#
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# Input: nums1 = [2,4], nums2 = [1,2,3,4]
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# Output: [3,-1]
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#
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# Explanation:
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# For number 2 in the first array, the next greater number for it in the second array is 3.
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# For number 4 in the first array, there is no next greater number for it in the second array, so output -1.
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#
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# Approach: Brute Force
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#
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# Complexity Analysis
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#
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# Time complexity: O(m*n). The complete nums1 array (of size n) needs to be scanned for all the m elements of nums2 in the worst case.
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# Space complexity: O(1). No additional space since we're swapping elements in nums1 and returning the input array.
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# @param {Integer[]} nums1
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# @param {Integer[]} nums2
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# @return {Integer[]}
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def next_greater_element(nums1, nums2)
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nums1.each_with_index do |nums1_value, pointer1|
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max = 0
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pos_nums2 = nums2.find_index(nums1_value)
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nums2[pos_nums2..nums2.count].each do |nums2_value|
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if nums2_value > nums1_value
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max = nums2_value
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break
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end
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end
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nums1[pointer1] = (nums1_value < max ? max : -1)
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end
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nums1
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end
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nums1 = [4, 1, 2]
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nums2 = [1, 3, 4, 2]
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print next_greater_element(nums1, nums2)
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# Output: [-1,3,-1]
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nums1 = [2, 4]
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nums2 = [1, 2, 3, 4]
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print next_greater_element(nums1, nums2)
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# Output: [3,-1]
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