Package g1801_1900.s1865_finding_pairs_with_a_certain_sum

Class 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 Detail

      • FindSumPairs

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

    • Method Detail

      • add

        public void add​(int index,
                int val)

      • count

        public int count​(int tot)