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javascript - 计算幂和的问题

问题描述

这是任务。

给定一个数组，机器输出每个其他数字的总和到下一个数字的幂。
例如：
给定array [w, x, y, z]，输出将是

Math.pow( w, x ) + Math.pow( y, z ).

问题

找到机器给定数组的输出： [98, 45, 97, 36, 22, 62, 88, 71, 16, 20, 54, 59, 23, 31, 12, 23, 77, 39, 37, 51, 68、69、92、30]。

这是我用 JS 编写的代码，它给出了错误的结果，我得到的结果是

114358835056152121265337954120332072257784950757189251203243784344124732554136221997457574443949497638865858230505438357582978

这是错误的。

let a = [98, 45, 97, 36, 22, 62, 88, 71, 16, 20, 54, 59, 23, 31, 12, 23, 77, 39, 37, 51, 68, 69, 92, 30];
let s = 0,
  r = 1;
for (let i = 0; i <= 22; i = i + 2) {
  for (let j = 1; j <= a[i + 1]; j++) {
    r = multiply(r, a[i]);
  }
  s = sum(s, r);
  r = 1;
}

// Add big numbers as strings in order to avoid scientific (exponent) notation
function sum(arg1, arg2) {
  var sum = "";
  var r = 0;
  var a1, a2, i;

  if (arg1.length < arg2.length) {
    a1 = arg1;
    a2 = arg2;
  } else {
    a1 = arg2;
    a2 = arg1;
  }
  a1 = a1.toString().split("").reverse();
  a2 = a2.toString().split("").reverse();

  for (i = 0; i < a2.length; i++) {
    var t = ((i < a1.length) ? parseInt(a1[i]) : 0) + parseInt(a2[i]) + r;
    sum += t % 10;
    r = t < 10 ? 0 : Math.floor(t / 10);
  }

  if (r > 0)
    sum += r;
  sum = sum.split("").reverse();

  while (sum[0] == "0")
    sum.shift();

  return sum.length > 0 ? sum.join("") : Number("");
}


// Multiply big numbers as strings in order to avoid scientific (exponent) notation
function multiply(a, b) {
  var aa = a.toString().split('').reverse();
  var bb = b.toString().split('').reverse();

  var stack = [];

  for (var i = 0; i < aa.length; i++) {
    for (var j = 0; j < bb.length; j++) {
      var m = aa[i] * bb[j];
      stack[i + j] = (stack[i + j]) ? stack[i + j] + m : m;
    }
  }
  for (var i = 0; i < stack.length; i++) {
    var num = stack[i] % 10;
    var move = Math.floor(stack[i] / 10);
    stack[i] = num;

    if (stack[i + 1])
      stack[i + 1] += move;
    else if (move != 0)
      stack[i + 1] = move;
  }
  return stack.reverse().join('');
}
// Print the result
console.log(s);

标签： javascriptarraysstringnumber-formatting

解决方案

我建议使用大整数库：

let a = ...;
let s = bigInt()
for (var i = 0; i < a.length; i += 2) 
  s = s.plus(bigInt(a[i]).pow(bigInt(a[i+1])));

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