我正在写自己的karatsuba algh变种,但不能使它与真正的大整数一起工作
'use strict';
const karatsuba = function (x, y) {
if (x < 10 || y < 10) return x * y;
const strX = String(x);
const strY = String(y);
const n = Math.min(strX.length, strY.length);
const m = Math.ceil(n / 2);
const leftX = strX.slice(0, strX.length - m),
rightX = strX.slice(strX.length - m, strX.length),
leftY = strY.slice(0, strY.length - m),
rightY = strY.slice(strY.length - m, strY.length);
const prod1 = karatsuba(leftX, leftY),
prod2 = karatsuba(rightX, rightY),
prod3 = karatsuba(addAny(leftX, rightX), addAny(leftY, rightY));
const a = prod1 + String(Math.pow(10, 2 * m)).slice(1),
b = (prod3 - prod1 - prod2) + String(Math.pow(10, m)).slice(1),
ab = addAny(a, b);
return addAny(ab, prod2);
};
function addAny(a, b) {
const MAX_INT = 9007199254740992,
intA = parseInt(a),
intB = parseInt(b);
if ((intA + intB) < MAX_INT) return intA + intB;
return sumStrings(a + '', b + '');
}
function sumStrings(a, b) {
let res = '', c = 0;
a = a.split('');
b = b.split('');
while (a.length || b.length || c) {
c += ~~a.pop() + ~~b.pop();
res = c % 10 + res;
c = c > 9;
}
return res.replace(/^0+/, '');
}
它适用于像3957322621233333和5548313756335578这样的注册 但是,当我尝试使用它与大型整数像76715432964249374812219365555和32141964835273822784327848699719代码崩溃与
RangeError: Maximum call stack size exceeded
答案 0 :(得分:3)
你在通话中省略了引号,不是吗?
> katsuba(76715432964249374812219365555,32141964835273822784327848699719)
RangeError: Maximum call stack size exceeded
at karatsuba (repl:2:5)
at karatsuba (repl:16:15)
at karatsuba (repl:17:9)
at karatsuba (repl:17:9)
at karatsuba (repl:17:9)
at karatsuba (repl:17:9)
at karatsuba (repl:17:9)
at karatsuba (repl:17:9)
at karatsuba (repl:17:9)
at karatsuba (repl:17:9)
76715432964249374812219365555
大于5**53
,代码中的MAX_INT
。数字文字隐式转换为浮点数7.671543296424938e+28
,您的算法会以数字格式扼流。
然而,您的实现中存在一些错误,因为即使您使用字符串文字,计算结果也是错误的:
> karatsuba('76715432964249374812219365555', '32141964835273822784327848699719')
'1045731853714033916818600413783559075'
而不是
'2465784748659709650840276767201870909665028593909797886779045'