有人用上echo了吗？# PDA - 掌中宝
j*m
1 楼
A non-empty zero-indexed array A consisting of N integers is given.
A pair of integers (P, Q) is calledK-complementary in array A if 0 ≤ P, Q <
N and A[P] + A[Q] = K.
For example, consider array A such that:
A[0] = 1 A[1] = 8 A[2]= -3
A[3] = 0 A[4] = 1 A[5]= 3
A[6] = -2 A[7] = 4 A[8]= 5
The following pairs are 6-complementary in array A: (0,8), (1,6), (4,8), (5,
5), (6,1), (8,0), (8,4).
For instance, the pair (4,8) is 6-complementary because A[4] + A[8] = 1 + 5
= 6.
Write a function:
class Solution { public int solution(int K, int[] A); }
that, given an integer K and a non-empty zero-indexed array A consisting of
N integers, returns the number of K-complementary pairs in array A.
For example, given K = 6 and array A such that:
A[0] = 1 A[1] = 8 A[2]= -3
A[3] = 0 A[4] = 1 A[5]= 3
A[6] = -2 A[7] = 4 A[8]= 5
the function should return 7, as explained above.
Assume that:
N is an integer within the range [1..50,000];
K is an integer within the range [−2,147,483,648..2,147,483,647];
each element of array A is an integer within the range [−2,147,483,648
..2,147,483,647].
Complexity:
expected worst-case time complexity is O(N*log(N));
expected worst-case space complexity is O(N), beyond input storage (not
counting the storage required for input arguments).
Elements of input arrays can be modified.
在网上看到的这题，和leetcode的two sum有点像，可是有重复元素， 而且要输出所有
这样的pair，我想不出除了O(N^2)的算法。
A pair of integers (P, Q) is calledK-complementary in array A if 0 ≤ P, Q <
N and A[P] + A[Q] = K.
For example, consider array A such that:
A[0] = 1 A[1] = 8 A[2]= -3
A[3] = 0 A[4] = 1 A[5]= 3
A[6] = -2 A[7] = 4 A[8]= 5
The following pairs are 6-complementary in array A: (0,8), (1,6), (4,8), (5,
5), (6,1), (8,0), (8,4).
For instance, the pair (4,8) is 6-complementary because A[4] + A[8] = 1 + 5
= 6.
Write a function:
class Solution { public int solution(int K, int[] A); }
that, given an integer K and a non-empty zero-indexed array A consisting of
N integers, returns the number of K-complementary pairs in array A.
For example, given K = 6 and array A such that:
A[0] = 1 A[1] = 8 A[2]= -3
A[3] = 0 A[4] = 1 A[5]= 3
A[6] = -2 A[7] = 4 A[8]= 5
the function should return 7, as explained above.
Assume that:
N is an integer within the range [1..50,000];
K is an integer within the range [−2,147,483,648..2,147,483,647];
each element of array A is an integer within the range [−2,147,483,648
..2,147,483,647].
Complexity:
expected worst-case time complexity is O(N*log(N));
expected worst-case space complexity is O(N), beyond input storage (not
counting the storage required for input arguments).
Elements of input arrays can be modified.
在网上看到的这题，和leetcode的two sum有点像，可是有重复元素， 而且要输出所有
这样的pair，我想不出除了O(N^2)的算法。
