Number of Pairs of Strings With Concatenation Equal to Target

export function numOfPairs(nums: string[], target: string): number {
  const n = nums.length;
  let answer = 0;
  for (let i = 0; i < n; i++) {
    for (let j = i + 1; j < n; j++) {
      if (nums[i] + nums[j] === target) {
        answer += 1;
      }
      if (nums[j] + nums[i] === target) {
        answer += 1;
      }
    }
  }
  return answer;
}

export function numOfPairs(nums: string[], target: string): number {
  const counter = new Map<string, number>();
  for (const num of nums) {
    counter.set(num, (counter.get(num) ?? 0) + 1);
  }
 
  let answer = 0;
  for (const [num, count] of counter) {
    if (!target.startsWith(num)) continue;
    const suffix = target.slice(num.length);
    if (num === suffix) {
      answer += count * (count - 1);
    } else {
      const suffixCount = counter.get(suffix) ?? 0;
      answer += count * suffixCount;
    }
  }
  return answer;
}