g1801_1900.s1865_finding_pairs_with_a_certain_sum

Class FindSumPairs

java.lang.Object

g1801_1900.s1865_finding_pairs_with_a_certain_sum.FindSumPairs

public class FindSumPairs
extends Object

1865 - Finding Pairs With a Certain Sum.

Medium

You are given two integer arrays nums1 and nums2. You are tasked to implement a data structure that supports queries of two types:

1. Add a positive integer to an element of a given index in the array nums2.
2. Count the number of pairs (i, j) such that nums1[i] + nums2[j] equals a given value (0 <= i < nums1.length and 0 <= j < nums2.length).

Implement the FindSumPairs class:

• FindSumPairs(int[] nums1, int[] nums2) Initializes the FindSumPairs object with two integer arrays nums1 and nums2.
• void add(int index, int val) Adds val to nums2[index], i.e., apply nums2[index] += val.
• int count(int tot) Returns the number of pairs (i, j) such that nums1[i] + nums2[j] == tot.

Example 1:

Input [“FindSumPairs”, “count”, “add”, “count”, “count”, “add”, “add”, “count”] [[[1, 1, 2, 2, 2, 3], [1, 4, 5, 2, 5, 4]], [7], [3, 2], [8], [4], [0, 1], [1, 1], [7]]

Output: [null, 8, null, 2, 1, null, null, 11]

Explanation:

FindSumPairs findSumPairs = new FindSumPairs([1, 1, 2, 2, 2, 3], [1, 4, 5, 2, 5, 4]);

findSumPairs.count(7); // return 8; pairs (2,2), (3,2), (4,2), (2,4), (3,4), (4,4) make 2 + 5 and pairs (5,1), (5,5) make 3 + 4

findSumPairs.add(3, 2); // now nums2 = [1,4,5, 4,5,4]

findSumPairs.count(8); // return 2; pairs (5,2), (5,4) make 3 + 5

findSumPairs.count(4); // return 1; pair (5,0) makes 3 + 1

findSumPairs.add(0, 1); // now nums2 = [**2 ** ,4,5,4,5,4]

findSumPairs.add(1, 1); // now nums2 = [2, 5 ,5,4,5,4]

findSumPairs.count(7); // return 11; pairs (2,1), (2,2), (2,4), (3,1), (3,2), (3,4), (4,1), (4,2), (4,4) make 2 + 5 and pairs (5,3), (5,5) make 3 + 4

Constraints:

• 1 <= nums1.length <= 1000
• 1 <= nums2.length <= 105
• 1 <= nums1[i] <= 109
• 1 <= nums2[i] <= 105
• 0 <= index < nums2.length
• 1 <= val <= 105
• 1 <= tot <= 109
• At most 1000 calls are made to add and count each.

Constructor Summary

Constructors

Constructor and Description
FindSumPairs(int[] nums1, int[] nums2)

Method Summary

Modifier and Type	Method and Description
void	add(int index, int val)
int	count(int tot)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FindSumPairs

public FindSumPairs(int[] nums1,
                    int[] nums2)

Method Detail

add

public void add(int index,
                int val)

count

public int count(int tot)