1. 合并二维有序数组成一维有序数组，归并排序的思路

  1. const arr = [
  2.     [2, 3, 4],
  3.     [4, 6, 7],
  4.     [5, 9, 23]
  5. ]

思路

  • 按照数组首项大小排序
  • 然后按照归并排序排序进行排序
  • 需要注意的是，划分到最细是两个长度为1的二维数组进行比较，需要降维处理

    实现

    1. function flat(arr) {
    2.   //按照首项大小进行比较
    3.   arr.sort((a, b) => a[0] - b[0]);
    4.   return mergeSort(arr);
    5. }
    6. function mergeSort(arr) {
    7.   if (arr.length < 2) return arr;
    8.   let mid = Math.floor(arr.length / 2);
    9.   let left = arr.slice(0, mid);
    10.   let right = arr.slice(mid);
    11.   return merge(mergeSort(left), mergeSort(right));
    12. }
    13. function merge(left, right) {
    14.   if (Array.isArray(left[0])) {
    15.       left = left[0];
    16.   }
    17.   if (Array.isArray(right[0])) {
    18.       right = right[0];
    19.   }
    20.   let tmp = [];
    21.   //合并两个有序数组
    22.   while (left.length && right.length) {
    23.       if (left[0] < right[0]) {
    24.           tmp.push(left.shift());
    25.       } else {
    26.           tmp.push(right.shift());
    27.       }
    28.   }
    29.   while (left.length) {
    30.       tmp.push(left.shift());
    31.   }
    32.   while (right.length) {
    33.       tmp.push(right.shift());
    34.   }
    35.   return tmp;
    36. }
    37. //demo
    38. const arr = [
    39.   [2, 3, 4],
    40.   [4, 6, 7],
    41.   [5, 9, 23],
    42. ]
    43. console.log(mergeSort(arr));