# 大数乘法和大数加法
Issue
欢迎在 Gtihub Issue 中回答此问题: Issue 189 (opens new window)
Author
TODO
Author
var multiply = function (num1, num2) {
if (num1 === "0" || num2 === "0") {
return "0";
}
let num1s = num1.split("");
let num2s = num2.split("");
num1s.reverse();
num2s.reverse();
function add(a, b) {
a = a.split("").reverse();
b = b.split("").reverse();
let len = Math.max(a.length, b.length);
let c = 0;
let r = [];
for (let i = 0; i < len; i++) {
let d = Number(a[i] || 0) + Number(b[i] || 0) + c;
let e = 0;
if (d >= 10) {
e = d - 10;
c = 1;
} else {
e = d;
c = 0;
}
r[i] = e;
}
if (c === 1) {
r[r.length] = 1;
}
return r.reverse().join("");
}
let results = [];
for (let i = 0; i < num1s.length; i++) {
for (let j = 0; j < num2s.length; j++) {
let zero = Array.from({ length: i + j })
.fill(0)
.join("");
results.push(Number(num1s[i]) * Number(num2s[j]) + zero);
}
}
return results.reduce((acc, c) => {
return add(acc, c);
});
};