leetcode

commit e8a5a000382b7236e558e3e871d0dec79a955f2d
parent 321ae48f1860944804457bb0c8cc47ab0ebaaaec
Author: Jack Sangdahl <jack@pngu.org>
Date:   Sat,  5 Jul 2025 23:43:47 -0600

1865. finding pairs with a certain sum

Diffstat:
A
finding_pairs_certain_sum.py
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54
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1 file changed, 54 insertions(+), 0 deletions(-)
diff --git a/finding_pairs_certain_sum.py b/finding_pairs_certain_sum.py
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+# 1865. Finding Pairs With a Certain Sum
+from collections import Counter
+
+"""
+you are given two integer arrays 'nums1' and 'nums2'. you are tasked to
+implement a data structure that supports queries of two types: add a positive
+integer to an element of a given index in the array 'nums2', count the number
+of pairs '(i, j)' such that 'nums1[i] + nums2[i]' equals a given ('0 <= i <
+nums1.length' and '0 <= j < nums2.length') implement the 'FindSumPairs'
+class.
+"""
+
+
+class FindSumPairs(object):
+    def __init__(self, nums1, nums2):
+        """
+        :type nums1: List[int]
+        :type nums2: List[int]
+        """
+        self.nums1_dict = Counter(nums1)
+        self.nums2_dict = Counter(nums2)
+        self.nums2 = nums2
+
+    def add(self, index, val):
+        """
+        :type index: int
+        :type val: int
+        :rtype: None
+        """
+        prev = self.nums2[index]
+        self.nums2[index] += val
+        self.nums2_dict[prev] -= 1
+        self.nums2_dict[prev + val] += 1
+
+    def count(self, tot):
+        """
+        :type tot: int
+        :rtype: int
+        """
+        ans = 0
+        for i, j in self.nums1_dict.items():
+            ans += j * self.nums2_dict[tot - i]
+        return ans
+
+
+if __name__ == "__main__":
+    obj = FindSumPairs(nums1=[1, 1, 2, 2, 2, 3], nums2=[1, 4, 5, 2, 5, 4])
+    print(obj.count(7))
+    print(obj.add(3, 2))
+    print(obj.count(8))
+    print(obj.count(4))
+    print(obj.add(0, 1))
+    print(obj.add(1, 1))
+    print(obj.count(7))