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.

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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"

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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.

難度應(yīng)該是easy題目啊，不應(yīng)該是中等難度的。。。

Runtime34 ms

Beats

46.60%

Memory42.4 MB

Beats

77.72%