HDU 1002 A + B Problem II（大整数相加）

A + B Problem II

Time Limit:1000MS     Memory Limit:32768KB     64bit IO Format:%I64d
& %I64u

Description

I have a very simple problem for you. Given two integers A and B, your job is to calculate the Sum of A + B.

Input

The first line of the input contains an integer T(1<=T<=20) which means the number of test cases. Then T lines follow, each line consists of two positive integers, A and B. Notice that the integers are very large, that means you should
not process them by using 32-bit integer. You may assume the length of each integer will not exceed 1000.

Output

For each test case, you should output two lines. The first line is "Case #:", # means the number of the test case. The second line is the an equation "A + B = Sum", Sum means the result of A + B. Note there are some spaces int the
equation. Output a blank line between two test cases.

Sample Input

 2
1 2
112233445566778899 998877665544332211 

Sample Output

 Case 1:
1 + 2 = 3

Case 2:
112233445566778899 + 998877665544332211 = 1111111111111111110 

题目大意：

大整数相加。

解题思路：

先把短的补齐。从最后一位開始计算。不进为就直接放进容器，进为把取余的放进容器，然后前一位加一。

代码：

#include<iostream>
#include<string>
#include<cstdio>
#include<vector>

using namespace std;

int t;
string str1,str2;
vector <char> v;

void solve(){
    string temp;
    int a,l2;
    if(str1.length()<str2.length()){
        temp=str1;str1=str2;str2=temp;
        l2=str2.length();
    }
    for(int i=0;i<str1.length()-l2;i++){
        str2.insert(0,1,'0');
    }
    for(int i=0;i<str1.length();i++){
        a=str1[str1.length()-i-1]+str2[str2.length()-i-1]-2*'0';
        if(a>=10){
            v.push_back(a%10+'0');
            if(str1.length()-i-1==0){
                v.push_back('1');break;
            }
            str1[str1.length()-i-2]=(char)(str1[str1.length()-i-2]+1);
        }
        else v.push_back((char)(a+'0'));
    }
     vector<char>::iterator it=v.end();
     it--;
     while(it!=v.begin()){
        if(*it=='0')
            v.erase(it);
        else break;
        it--;
     }
    for(int i=v.size()-1;i>=0;i--){
       cout<<v[i];
    }
    cout<<endl;
}

int main(){
    int casen=0;
    scanf("%d",&t);
    while(t-->0){
        cin>>str1>>str2;
        printf("Case %d:\n%s + %s = ",++casen,str1.c_str(),str2.c_str());
        v.clear();
        solve();
        if(t!=0)
            cout<<endl;
    }
    return 0;
}