Watch 10 video solutions for Number of Pairs of Strings With Concatenation Equal to Target, a medium level problem involving Array, Hash Table, String. This walkthrough by NeetCode has 611,579 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
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: 4 Explanation: 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: 2 Explanation: Valid pairs are: - (0, 1): "123" + "4" - (2, 3): "12" + "34"
Example 3:
Input: nums = ["1","1","1"], target = "11" Output: 6 Explanation: 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 <= 1001 <= nums[i].length <= 1002 <= target.length <= 100nums[i] and target consist of digits.nums[i] and target do not have leading zeros.