2023. Number of Pairs of Strings With Concatenation Equal to Target LeetCode Solution
In this guide, you will get 2023. Number of Pairs of Strings With Concatenation Equal to Target LeetCode Solution with the best time and space complexity. The solution to Number of Pairs of Strings With Concatenation Equal to Target problem is provided in various programming languages like C++, Java, and Python. This will be helpful for you if you are preparing for placements, hackathons, interviews, or practice purposes. The solutions provided here are very easy to follow and include detailed explanations.
Problem Statement of Number of Pairs of Strings With Concatenation Equal to Target
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.
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.
Complexity Analysis
Time Complexity: O(|\texttt{nums}|)
Space Complexity: O(|\texttt{nums}|)
2023. Number of Pairs of Strings With Concatenation Equal to Target LeetCode Solution in C++
class Solution {
public:
int numOfPairs(vector<string>& nums, string target) {
const int n = target.length();
int ans = 0;
unordered_map<string, int> count;
for (const string& num : nums) {
const int k = num.length();
if (k >= n)
continue;
if (target.substr(0, k) == num)
ans += count[target.substr(k)];
if (target.substr(n - k) == num)
ans += count[target.substr(0, n - k)];
++count[num];
}
return ans;
}
}; /* code provided by PROGIEZ */
2023. Number of Pairs of Strings With Concatenation Equal to Target LeetCode Solution in Java
class Solution {
public int numOfPairs(String[] nums, String target) {
final int n = target.length();
int ans = 0;
Map<String, Integer> count = new HashMap<>();
for (final String num : nums) {
final int k = num.length();
if (k >= n)
continue;
if (target.substring(0, k).equals(num))
ans += count.getOrDefault(target.substring(k), 0);
if (target.substring(n - k).equals(num))
ans += count.getOrDefault(target.substring(0, n - k), 0);
count.merge(num, 1, Integer::sum);
}
return ans;
}
} // code provided by PROGIEZ
2023. Number of Pairs of Strings With Concatenation Equal to Target LeetCode Solution in Python
class Solution:
def numOfPairs(self, nums: list[str], target: str) -> int:
ans = 0
count = collections.Counter()
for num in nums:
k = len(num)
if target[:k] == num:
ans += count[target[k:]]
if target[-k:] == num:
ans += count[target[:-k]]
count[num] += 1
return ans # code by PROGIEZ
