# 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))
