Javascript 乘以字符串
Javascript multiplying strings
我正在按照 leetcode question 做乘法
Given two non-negative integers num1 and num2 represented as strings, return the
product of num1 and num2, also represented as a string.
Note: You must not use any built-in BigInteger library or convert the inputs to
integer directly.
Example 1:
Input: num1 = "2", num2 = "3"
Output: "6"
Example 2:
Input: num1 = "123", num2 = "456"
Output: "56088"
Constraints:
- 1 <= num1.length, num2.length <= 200
- num1 and num2 consist of digits only.
- Both num1 and num2 do not contain any leading zero, except the number 0 itself.
为此使用了以下方法
- 将字符串转换为整数
- 整数相乘
相同的算法是
const numberMap = {
"0": 0,
"1": 1,
"2": 2,
"3": 3,
"4": 4,
"5": 5,
"6": 6,
"7": 7,
"8": 8,
"9": 9
}
var multiply = function(num1, num2) {
let i = num1.length
let j = num2.length
let sum = currentPower = 0
let firstNumber = secondNumber = 0
while(i > 0 || j > 0) {
// if I or J is equal to zero, means we have itterated hence we will set the value to one
const firstNum = i > 0 ? (numberMap[num1[i-1]]) * (10**currentPower) : 0
const secondNum = j > 0 ? (numberMap[num2[j-1]]) * (10**currentPower) : 0
firstNumber += firstNum
secondNumber += secondNum
currentPower++
i--
j--
}
sum = firstNumber * secondNumber
return sum.toString()
};
但是当给出以下输入时
"123456789"
"987654321"
它产生以下输出 "121932631112635260"
而不是 "121932631112635269"
知道如何解决这个问题吗?
您可以将每个数字与其他数字相乘,并将索引作为位置。
Like you would do by hand, like
1 2 3 4 * 4 3 2 1
-------------------------
1 2 3 4
1 4 6 8
3 6 9 12
4 8 12 16
-------------------------
5 3 2 2 1 1 4
此方法使用字符串的反转数组,并反转结果集。
在重新调整结果之前,数组由前导零过滤。
function multiply(a, b) {
var aa = [...a].reverse(),
bb = [...b].reverse(),
p = [],
i, j;
for (i = 0; i < aa.length; i++) {
for (j = 0; j < bb.length; j++) {
if (!p[i + j]) p[i + j] = 0;
p[i + j] += aa[i] * bb[j];
if (p[i + j] > 9) {
if (!p[i + j + 1]) p[i + j + 1] = 0;
p[i + j + 1] += Math.floor(p[i + j] / 10);
p[i + j] %= 10;
}
}
}
return p
.reverse()
.filter((valid => (v, i, { length }) => valid = +v || valid || i + 1 === length)(false))
.join('');
}
console.log(multiply('2', '3')); // 6
console.log(multiply('123', '456')); // 56088
console.log(multiply('9133', '0')); // 0
console.log(multiply('9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999', '9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999'));
只需转换为数字,相乘,然后再转换回字符串。
function mult(a, b){
return (Number(a) * Number(b)).toString();
}
在JavaScript中,整数不是特定类型。它们是数字类型。我们可以使用 parseInt() 函数而不是 Number() 函数来进行转换,但我们知道无论如何我们都会收到一个 int 作为输入,所以不需要那种解析。
var multiply = function(num1, num2) {
let v1=BigInt(num1)
let v2=BigInt(num2)
let v3=v1*v2
return v3.toString()
};
function multiply() {
var str = document.getElementById('a').value;
var str1 = document.getElementById('b').value;
var l = str.length;
var l1 = str1.length;
var list = [];
var prod = 0;
var cur = 0;
list.length = l + l1;
// store 0 to to all list elements
list.fill(0);
// access string in reverse
for (var i = l - 1; i >= 0; i--) {
for (
var j = l1 - 1;
j >= 0;
j-- // access string in reverse
) {
// ASCII value of character and - ("0") ASCII Value 48
prod = (str.charCodeAt(i) - 48) * (str1.charCodeAt(j) - 48);
cur = list[i + j + 1] + prod;
list[i + j + 1] = cur % 10;
list[i + j] += parseInt(cur / 10);
}
}
var res = '';
res = list.join('');
if (res[0] == 0) {
// if First Char ==0 then remove
res = res.slice(1);
}
console.log(res);
}
我正在按照 leetcode question 做乘法
Given two non-negative integers num1 and num2 represented as strings, return the
product of num1 and num2, also represented as a string.
Note: You must not use any built-in BigInteger library or convert the inputs to
integer directly.
Example 1:
Input: num1 = "2", num2 = "3"
Output: "6"
Example 2:
Input: num1 = "123", num2 = "456"
Output: "56088"
Constraints:
- 1 <= num1.length, num2.length <= 200
- num1 and num2 consist of digits only.
- Both num1 and num2 do not contain any leading zero, except the number 0 itself.
为此使用了以下方法
- 将字符串转换为整数
- 整数相乘
相同的算法是
const numberMap = {
"0": 0,
"1": 1,
"2": 2,
"3": 3,
"4": 4,
"5": 5,
"6": 6,
"7": 7,
"8": 8,
"9": 9
}
var multiply = function(num1, num2) {
let i = num1.length
let j = num2.length
let sum = currentPower = 0
let firstNumber = secondNumber = 0
while(i > 0 || j > 0) {
// if I or J is equal to zero, means we have itterated hence we will set the value to one
const firstNum = i > 0 ? (numberMap[num1[i-1]]) * (10**currentPower) : 0
const secondNum = j > 0 ? (numberMap[num2[j-1]]) * (10**currentPower) : 0
firstNumber += firstNum
secondNumber += secondNum
currentPower++
i--
j--
}
sum = firstNumber * secondNumber
return sum.toString()
};
但是当给出以下输入时
"123456789"
"987654321"
它产生以下输出 "121932631112635260"
而不是 "121932631112635269"
知道如何解决这个问题吗?
您可以将每个数字与其他数字相乘,并将索引作为位置。
Like you would do by hand, like
1 2 3 4 * 4 3 2 1 ------------------------- 1 2 3 4 1 4 6 8 3 6 9 12 4 8 12 16 ------------------------- 5 3 2 2 1 1 4
此方法使用字符串的反转数组,并反转结果集。
在重新调整结果之前,数组由前导零过滤。
function multiply(a, b) {
var aa = [...a].reverse(),
bb = [...b].reverse(),
p = [],
i, j;
for (i = 0; i < aa.length; i++) {
for (j = 0; j < bb.length; j++) {
if (!p[i + j]) p[i + j] = 0;
p[i + j] += aa[i] * bb[j];
if (p[i + j] > 9) {
if (!p[i + j + 1]) p[i + j + 1] = 0;
p[i + j + 1] += Math.floor(p[i + j] / 10);
p[i + j] %= 10;
}
}
}
return p
.reverse()
.filter((valid => (v, i, { length }) => valid = +v || valid || i + 1 === length)(false))
.join('');
}
console.log(multiply('2', '3')); // 6
console.log(multiply('123', '456')); // 56088
console.log(multiply('9133', '0')); // 0
console.log(multiply('9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999', '9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999'));
只需转换为数字,相乘,然后再转换回字符串。
function mult(a, b){
return (Number(a) * Number(b)).toString();
}
在JavaScript中,整数不是特定类型。它们是数字类型。我们可以使用 parseInt() 函数而不是 Number() 函数来进行转换,但我们知道无论如何我们都会收到一个 int 作为输入,所以不需要那种解析。
var multiply = function(num1, num2) {
let v1=BigInt(num1)
let v2=BigInt(num2)
let v3=v1*v2
return v3.toString()
};
function multiply() {
var str = document.getElementById('a').value;
var str1 = document.getElementById('b').value;
var l = str.length;
var l1 = str1.length;
var list = [];
var prod = 0;
var cur = 0;
list.length = l + l1;
// store 0 to to all list elements
list.fill(0);
// access string in reverse
for (var i = l - 1; i >= 0; i--) {
for (
var j = l1 - 1;
j >= 0;
j-- // access string in reverse
) {
// ASCII value of character and - ("0") ASCII Value 48
prod = (str.charCodeAt(i) - 48) * (str1.charCodeAt(j) - 48);
cur = list[i + j + 1] + prod;
list[i + j + 1] = cur % 10;
list[i + j] += parseInt(cur / 10);
}
}
var res = '';
res = list.join('');
if (res[0] == 0) {
// if First Char ==0 then remove
res = res.slice(1);
}
console.log(res);
}