28 lines
659 B
Ruby
28 lines
659 B
Ruby
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#Given an array arr[], find the maximum j – i such that arr[j] > arr[i].
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# Time-complecity: O(n), Space-complexity:O(n)
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def max_index_diff(a)
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len=a.length
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max_diff=-1
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lmin=Array.new(len)
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rmax=Array.new(len)
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lmin[0]=a[0]
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for i in 1...len
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lmin[i]=[a[i],lmin[i-1]].min
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end
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rmax[len-1]=a[len-1]
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for i in (len-2).downto(0)
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rmax[i]=[a[i],rmax[i+1]].max
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end
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i=j=0
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while (j<len && i<len)
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if lmin[i]<rmax[j]
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max_diff=[max_diff,j-i].max
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j+=1
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else
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i+=1
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end
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end
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return max_diff
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end
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max_index_diff([34, 8, 10, 3, 2, 80, 30, 33, 1]) # => 6
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