在多个数组中查找交集

function findIntersection(arrays) {
  if (arrays.length === 0) return [];
  let intersection = new Set(arrays[0]);
  for (let i = 1; i < arrays.length; i++) {
    intersection = new Set([...intersection].filter(x => arrays[i].includes(x)));
  }
  return Array.from(intersection);
}

// 示例
const arrays = [
  [1, 2, 3, 4],
  [2, 3, 4, 5],
  [3, 4, 5, 6]
];
console.log(findIntersection(arrays)); // 输出: [3, 4]

function findIntersection(arrays) {
  if (arrays.length === 0) return [];
  const map = new Map();
  for (let array of arrays) {
    for (let num of array) {
      if (!map.has(num)) {
        map.set(num, 1);
      } else {
        map.set(num, map.get(num) + 1);
      }
    }
  }
  const intersection = [];
  for (let [num, count] of map.entries()) {
    if (count === arrays.length) {
      intersection.push(num);
    }
  }
  return intersection;
}

// 示例
const arrays = [
  [1, 2, 3, 4],
  [2, 3, 4, 5],
  [3, 4, 5, 6]
];
console.log(findIntersection(arrays)); // 输出: [3, 4]