题干

C++实现

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<map>
#include<string>
using namespace std;

string GetInteger(string a) {
	return a.substr(0, a.find('.'));
}

string GetFraction(string a) {
	return a.substr(a.find('.') +1 ,a.size() - a.find('.'));
}

//利用引用参数，返回多个信息
void FractionPlus(string& res, int& carry, string fa, string fb) {
	int size = max(fa.size(), fb.size());
	//将两个数的小数部分对齐
	while (fa.size() < size) {
		fa.push_back('0');
	}
	while (fb.size() < size) {
		fb.push_back('0');
	}

	res.resize(size);//给res申请内存
	carry = 0;

	//从右往左加
	for (int i = size - 1; i >= 0; i--)
	{
		// '0' = '0'
		// '3' = '0' + 3

		if (fa[i] + fb[i] + carry - '0' > '9') {
			res[i] = fa[i] + fb[i] + carry - '0' - 10;
			carry = 1;
		}
		else {
			res[i] = fa[i] + fb[i] + carry - '0';
			carry = 0;
		}
	}

	return;
}

void IntegerPlus(string& res, int carry, string ia, string ib) {
	res.clear();//清空字符串
	for (int i = ia.size() - 1, j = ib.size() - 1; i >= 0 || j >= 0 || carry == 1; --i, --j) {
		if (i >= 0 && j >= 0) {
			if (ia[i] + ib[j] + carry - '0' > '9') {
				res.insert(res.begin(), ia[i] + ib[j] + carry - '0' - 10);
				carry = 1;
			}
			else {
				res.insert(res.begin(), ia[i] + ib[j] + carry - '0');
				carry = 0;
			}
		}
		else if (i >= 0 && j < 0) {
			if (ia[i] + carry > '9') {
				res.insert(res.begin(), ia[i] + carry - 10);
				carry = 1;
			}
			else {
				res.insert(res.begin(), ia[i] + carry);
				carry = 0;
			}
		}
		else if(i < 0 && j >= 0){
			if (ib[j] + carry > '9') {
				res.insert(res.begin(), ib[j] + carry - 10);
				carry = 1;
			}
			else {
				res.insert(res.begin(), ib[j] + carry);
				carry = 0;
			}
		}
		else {
			res.insert(res.begin(), '1');
			carry = 0;
		}
	}

 	return;
}

int main() {
	/*string a = "12345.6789";
	string b = "333.33333";*/

	char arra[1024];
	char arrb[1024];

	while (scanf("%s%s", arra, arrb) != EOF) {
		string a = arra;
		string b = arrb;

		string ia = GetInteger(a);
		string ib = GetInteger(b);
		string fa = GetFraction(a);
		string fb = GetFraction(b);

		string res;
		int carry;
		FractionPlus(res, carry, fa, fb);
		string ires;
		IntegerPlus(ires, carry, ia, ib);

		printf("%s.%s\n", ires.c_str(), res.c_str());
	}

	return 0;
}