LeetCode-in-Java
2023. Number of Pairs of Strings With Concatenation Equal to Target
Medium
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]andtargetconsist of digits.nums[i]andtargetdo not have leading zeros.
Solution
public class Solution {
public int numOfPairs(String[] nums, String target) {
int ans = 0;
for (int i = 0; i < nums.length; i++) {
for (int j = 0; j < nums.length; j++) {
if (i != j) {
String con = nums[i] + nums[j];
if (con.equals(target)) {
ans++;
}
}
}
}
return ans;
}
}