16 lines
387 B
Python
16 lines
387 B
Python
def countFairPairs(self, nums, lower, upper):
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nums.sort()
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ans = 0
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def pairs_leq(x: int) -> int:
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pairs = 0
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l, r = 0, len(nums) - 1
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while l < r:
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if nums[l] + nums[r] <= x:
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pairs += r - l
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l += 1
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else:
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r -= 1
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return pairs
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return pairs_leq(upper) - pairs_leq(lower - 1)
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