53 lines
1.0 KiB
Markdown
53 lines
1.0 KiB
Markdown
## 1、求N！的值 【问题描述】
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用高精度方法，求N！的精确值(N以一般整数输入)。
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【输入样例】ni.in
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```in
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10
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```
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【输出样例】ni.out
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```out
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3628800
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```
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```cpp
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#include<iostream>
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#include<string>
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#include<vector>
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using namespace std;
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// 高精度字符串乘法：res * num
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string multiply(string res, int num) {
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vector<int> temp;
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int carry = 0;
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for (int i = res.size() - 1; i >= 0; i--) {
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int product = (res[i] - '0') * num + carry;
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temp.push_back(product % 10);
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carry = product / 10;
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}
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while (carry) {
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temp.push_back(carry % 10);
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carry /= 10;
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}
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// 把结果翻转回来
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string result;
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for (int i = temp.size() - 1; i >= 0; i--) {
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result += temp[i] + '0';
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}
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return result;
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}
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int main() {
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int n;
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cin >> n;
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string result = "1";
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for (int i = 2; i <= n; i++) {
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result = multiply(result, i);
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}
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reverse(result.begin(), result.end());
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cout << result << endl;
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return 0;
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}
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``` |