Transpose

查看解答我的解答

题目

The transpose of a matrix is an operator which flips a matrix over its diagonal; that is, it switches the row and column indices of the matrix A by producing another matrix, often denoted by A^T.

type Matrix = Transpose<[[1]]>; // expected to be [[1]]
type Matrix1 = Transpose<[[1, 2], [3, 4]]>; // expected to be [[1, 3], [2, 4]]
type Matrix2 = Transpose<[[1, 2, 3], [4, 5, 6]]>; // expected to be [[1, 4], [2, 5], [3, 6]]

解答

type Transpose<M extends number[][], R = M["length"] extends 0 ? [] : M[0]> = {
  [X in keyof R]: {
    [Y in keyof M]: X extends keyof M[Y] ? M[Y][X] : never;
  };
};