题解 | #幂运算#

以下代码可以通过，主要思路是用字符串string来实现乘法，代码如下，写得不好的地方huan'ying'pi***'zhi'zheng

#include<iostream>
#include<string>
#include<vector>
using namespace std;

string myMultiplyString(string strU, string strB) {
    int numU = strU.size();
    int numB = strB.size();

    vector<int> mulResInt(numB+numU,0);
    int numVecResInt = mulResInt.size();
    int intU, intB;
    for (int b = numB-1; b >= 0; b--) {   // 下面的因子
        for (int u = numU - 1; u >= 0; u--) { // 上面的因子
            intU = strU[u] - '0';
            intB = strB[b] - '0';
            mulResInt[numB+numU -2-(u + b)] += intU * intB;
        }
    }
    // 开始进位
    for (int k = 0; k < numB+numU -1; k++) {
        mulResInt[k + 1] += mulResInt[k] / 10;
        mulResInt[k] %= 10;
    }
    int numVecResStr;
    if (mulResInt[numVecResInt - 1] == 0)numVecResStr = numVecResInt-1;
    else numVecResStr = numVecResInt;
    string mulResStr(numVecResStr, '0');
    // 组合成字符串
    for (int k = 0; k < numVecResStr; k++) {
        mulResStr[numVecResStr - k - 1] += mulResInt[k];
    }
    return mulResStr;
}

string mypow(string R, int n) {
    string powRes = "1";
    for (int i = 0; i < n; i++) {
        powRes = myMultiplyString(powRes, R);
    }
    return powRes;
}

int mydelPoint(string &str) {
    // 如果字符串小数部分末尾几位是0，则先去除
    int numXiaoshu = 0;
    auto pointPos = str.find('.');

    if (pointPos != string::npos) {
        int n = str.size();
        while (str[n - 1] == '0') {
            n--;
        }
        str.erase(str.begin() + n, str.end());
        numXiaoshu = str.size() - pointPos - 1;
        str.erase(str.begin() + pointPos, str.begin() + pointPos + 1);
    }
    return numXiaoshu;
}

void myaddPoint(string &str, int pos) {
    str.insert(pos, ".");
}

int main() {

    string R;
    int n;
    vector<string> Rvec;
    vector<int> nvec;
    while (cin >> R >> n) {
        Rvec.push_back(R);
        nvec.push_back(n);
        if (cin.get() == '\n')break;
    }
    if (Rvec.size() != nvec.size())return 0;

    int iniNumXSInt,powNumXSInt;
    string iniNumXSStr;
    for (int i = 0; i < Rvec.size(); i++) {
        iniNumXSInt = mydelPoint(Rvec[i]);
        string temp = mypow(Rvec[i], nvec[i]);
        if (iniNumXSInt > 0) {
            powNumXSInt = temp.size() - nvec[i] * iniNumXSInt;
            myaddPoint(temp, powNumXSInt);
        }
        cout << temp;
    }
    cout << endl;
    return 0;
}