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## 关于$\_\_int128$的使用
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正常来说，`unsigned long long`已经是可以定义的最大的类型了，但是如果数据范围超过了$2^64$就会爆炸。如果要处理比其大一点又不是那么大的数，就可以使用`__int128`这个定义。
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$NOI$及$CSP$系列中可以正常使用`__int128`:
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https://www.cnblogs.com/littlehb/p/15935662.html
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$\_\_int128$ 就是占用$128$字节的整数存储类型。由于是二进制，范围就是 $(-2^{127}) \sim (2^{127}-1)$，
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如果使用了 `unsigned __int128`，则范围变成 $(0) ~ (2^{128})$，即约$39$位数！
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由于 `__int128` 仅仅是 $(GCC)$ 编译器内的东西，不在 $(C++ 98/03/11/14/17/20)$ 标准内，且仅 $(GCC4.6)$ 以上$64$位版本支持，很多配套都没有，只有四则运算功能, 所以要自己写输入输出。使用方法与 $int$ $long$ $long$无异
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<font color='red'><b>注意：如何确定考试中能不能用$int128$呢？办法就是先创建一个空白的$cpp$文件，然后使用 `__int128 a;`，测试一下，编译器不报错就是可以。</b></font>
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``` c++
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#include <bits/stdc++.h>
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using namespace std;
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typedef unsigned __int128 LLL;
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LLL read() {
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LLL x = 0, f = 1;
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char ch = getchar();
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while (ch < '0' || ch > '9') {
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if (ch == '-') f = -1;
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ch = getchar();
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}
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while (ch >= '0' && ch <= '9') {
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x = x * 10 + ch - '0';
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ch = getchar();
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}
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return x * f;
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}
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void out(LLL x) {
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if (x < 0) putchar('-'), x = -x;
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if (x > 9) out(x / 10);
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putchar(x % 10 + '0');
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}
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int main() {
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LLL a, b;
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a = read(), b = read();
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out(a + b);
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return 0;
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}
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```
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