Leetcode2023. Number of Pairs of Strings With Concatenation Equa

Given an array of digit strings nums and a digit string target, return the number of pairs of indices (i, j) (where i != j) such that the concatenation of nums[i] + nums[j] equals target.

Example 1:

Input: nums = ["777","7","77","77"], target = "7777"Output: 4Explanation: Valid pairs are: - (0, 1): "777" + "7" - (1, 0): "7" + "777" - (2, 3): "77" + "77" - (3, 2): "77" + "77"

Example 2:

Input: nums = ["123","4","12","34"], target = "1234"Output: 2Explanation: Valid pairs are: - (0, 1): "123" + "4" - (2, 3): "12" + "34"

Example 3:

Input: nums = ["1","1","1"], target = "11"Output: 6Explanation: Valid pairs are: - (0, 1): "1" + "1" - (1, 0): "1" + "1" - (0, 2): "1" + "1" - (2, 0): "1" + "1" - (1, 2): "1" + "1" - (2, 1): "1" + "1"

Constraints:

• 2 <= nums.length <= 100

• 1 <= nums[i].length <= 100

• 2 <= target.length <= 100

• nums[i] and target consist of digits.

• nums[i] and target do not have leading zeros.

难度应该是easy题目啊，不应该是中等难度的。。。

Runtime34 ms

Beats

46.60%

Memory42.4 MB

Beats

77.72%