js 两个数组差

// 左差集（A - B）
function leftDifference(arr1, arr2) {
  return arr1.filter(item => !arr2.includes(item));
}

// 右差集（B - A）
function rightDifference(arr1, arr2) {
  return arr2.filter(item => !arr1.includes(item));
}

// 对称差集（A ∆ B）
function symmetricDifference(arr1, arr2) {
  const leftDiff = leftDifference(arr1, arr2);
  const rightDiff = rightDifference(arr1, arr2);
  return [...new Set([...leftDiff, ...rightDiff])];
}

// 示例
const array1 = [1, 2, 3, 4];
const array2 = [3, 4, 5, 6];

console.log('左差集:', leftDifference(array1, array2)); // 输出: [1, 2]
console.log('右差集:', rightDifference(array1, array2)); // 输出: [5, 6]
console.log('对称差集:', symmetricDifference(array1, array2)); // 输出: [1, 2, 5, 6]

function optimizedDifference(arr1, arr2) {
  const set2 = new Set(arr2);
  return arr1.filter(item => !set2.has(item));
}

// 示例
console.log('优化后的左差集:', optimizedDifference(array1, array2)); // 输出: [1, 2]