Project Euler problem 48 处理乘法取模爆long long的方法

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呵呵这题的猥琐之处在于你用快速幂中间过程都有可能爆了long long

不过我有处理爆long long 的方法

乘的时候用二分的方法去搞就没问题了。详见代码

#include <iostream>#include <cstdio>#include <cstring>#include <ctime>#include <cstdlib>#include <algorithm>#include <stack>#include <cmath>#include <vector>#define eps 1e-6#define INF 1000000007#define PI acos(-1.0)using namespace std;long long mod = 10000000000LL;long long multi(long long a, long long b, long long c){    long long ret = 0;    while(b)    {        if(b & 1)        {            ret += a;            if(ret >= c)                ret -= c;        }        a += a;        if(a >= c) a -= c;        b >>= 1;    }    return ret;}long long fastmod(long long a, long long b, long long c)//a^b mod c{    long long ret = 1;    a %= c;    for (; b; b >>= 1, a = multi(a, a, c))        if (b & 1)            ret = multi(ret, a, c);    return ret;}int main(){    long long sum = 0;    for(int i = 1; i <= 1000; i++)        sum = (sum + fastmod(i, i, mod)) % mod;    cout << sum << endl;    return 0;}