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qzda (2023/07/27)

# Currying add(1)(2)(3)

type TypeFunAdd = (...arg: number[]) => TypeFunAdd;

function add(...arg: number[]) {
  const f: TypeFunAdd = add.bind(null, ...arg);

  f.toString = () => arg.reduce((sum, i) => sum + i, 0).toString();

  return f;
}

add(1)(2)(3); // 6

type TypeFunAdd = (...arg: number[]) => TypeFunAdd;

function add(...arg: number[]) {
  const f: TypeFunAdd = add.bind(null, ...arg);

  f.toString = () => arg.reduce((sum, i) => sum + i, 0).toString();

  return f;
}

add(1)(2)(3); // 6

# Math.sqrt() implemented using Newton’s method

function mySqrt(x: number) {
  const precision = 0.1;
  let ans = x / 2,
    last;

  do {
    last = ans;
    ans = (ans + x / ans) / 2;
  } while (Math.abs(ans - last) > precision);

  return ans >> 0;
}

function mySqrt(x: number) {
  const precision = 0.1;
  let ans = x / 2,
    last;

  do {
    last = ans;
    ans = (ans + x / ans) / 2;
  } while (Math.abs(ans - last) > precision);

  return ans >> 0;
}

# Typescript: Range<0, 100>

type Max<
  N,
  A extends number[] = [0],
  B extends number[] = [],
> = B["length"] extends N ? B[number] : Max<N, [...A, 0], [...B, A["length"]]>;

type Min<N, A extends number[] = []> = A["length"] extends N
  ? A[number]
  : Min<N, [...A, A["length"]]>;

type Range<min, max> = Exclude<Max<max>, Min<min>>;

type t100_200 = Range<0, 100>;

type Max<
  N,
  A extends number[] = [0],
  B extends number[] = [],
> = B["length"] extends N ? B[number] : Max<N, [...A, 0], [...B, A["length"]]>;

type Min<N, A extends number[] = []> = A["length"] extends N
  ? A[number]
  : Min<N, [...A, A["length"]]>;

type Range<min, max> = Exclude<Max<max>, Min<min>>;

type t100_200 = Range<0, 100>;
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