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Diffstat (limited to 'count_nice_pair.py')
-rw-r--r-- | count_nice_pair.py | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/count_nice_pair.py b/count_nice_pair.py new file mode 100644 index 0000000..e3d7ecf --- /dev/null +++ b/count_nice_pair.py @@ -0,0 +1,32 @@ +# 1814. Count Nice Pairs in an Array +import collections + +""" +given an array 'nums' that consists of non-negative integers. let us define +'rev(x)' as the reverse of the non-negative integer 'x'. for example, +'rev(123) = 321' and 'rev(120) = 21'. a pair of indices '(i, j)' is nice if +it satisfies all of the following conditions: '0 <= i < j < nums.length' and +'nums[i] + rev(nums[j]) == nums[j] + rev(nums[i])'. return the number of nice +pairs of indices. since that number be very large, return it modulo 1e9+7 +""" + + +class Solution(object): + def countNicePairs(self, nums): + """ + :type nums: List[int] + :rtype: int + """ + ans = 0 + cnt = collections.Counter() + for i in nums: + b = int(str(i)[::-1]) + ans += cnt[i - b] + cnt[i - b] += 1 + return ans % (10**9 + 7) + + +if __name__ == "__main__": + obj = Solution() + print(obj.countNicePairs([42, 11, 1, 97])) # expect: 2 + print(obj.countNicePairs([13, 10, 35, 24, 76])) # expect: 4 |