aizu online judge link: http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=0002

DigitNumber.cpp

#include <iostream>
#include <string>
#include <cassert>
#include <sstream>
#include <vector>
#include "math.h"

template<typename T>
T string2binary(const std::string& text, int base)
{
    assert(base == 8 || base == 10 || base == 16);
    std::istringstream is(text);
    T value;
    switch (base) {
    case 8:  is >> std::oct >> value; break;
    case 10: is >> value;        break;
    case 16: is >> std::hex >> value; break;
    default: ;
    }
    return value;
}

void splitstring(const std::string& data, const char* delimiter, std::vector<std::string>& result)
{
    result.clear();
    if( data.empty() ) return;

    std::string::size_type pos = 0;
    std::string::size_type new_pos;
    while( ( new_pos = data.find( delimiter, pos)) != std::string::npos ){
        result.push_back( data.substr( pos, new_pos-pos ) );
        pos = new_pos+1;
    }
    result.push_back( data.substr( pos ) );
}

int numberOfDigit(int num){
    return (int)log10(num) + 1;
}
void print1DItem(std::vector<int>& vec){
    std::vector<int>::iterator it = vec.begin();
    for(; it !=  vec.end(); it++){
        std::cout << *it << std::endl;
    }
}

int main(){
    using namespace std;
    int ii = 0, count = 0;
    vector<int> result;
    std::string line;
    while(std::getline(cin, line)){
        // char in[256];
        // cin.getline(in, 256);
        // std::string str = in;
        if(line.size() == 0) break;
        // cout << line.size() << endl;
        std::vector<std::string> vec;
        // スペースをデリミターにして２つに分割
        splitstring(line, " ", vec);
        // ２つの数字を足し合わせる
        // vector<string>::iterator it = vec.begin();
        // for(; it !=  vec.end(); it++){
        //     cout << *it << endl;
        // }
        // cout << endl;
        int sum = string2binary<int>(vec[ii], 10)
            + string2binary<int>(vec[ii + 1], 10);
        // cout << numberOfDigit(sum) << endl;
        result.push_back(sum);
        // count++;
    }
    std::vector<int>::iterator it = result.begin();
    for(; it !=  result.end(); it++){
        cout << numberOfDigit(*it) << endl;
        // cout << numberOfDigit(*it);
    }
    // cout << numberOfDigit(*it);

}

list_of_top3_hills.cpp

#include <cassert>
#include <sstream>
#include <set>
#include <iostream>

template<typename T>
T string2binary(const std::string& text, int base)
{
    assert(base == 8 || base == 10 || base == 16);
    std::istringstream is(text);
    T value;
    switch (base) {
    case 8:  is >> std::oct >> value; break;
    case 10: is >> value;        break;
    case 16: is >> std::hex >> value; break;
    default: ;
    }
    return value;
}

int main(){
    std::string str;
    std::set<int> hills;
    while(getline(std :: cin, str)){
        if(str.size() == 0) break;
        // if(str == 0 || str == NULL)break;
        hills.insert(string2binary<int>(str, 10));
    }
    std::set<int>::reverse_iterator it = hills.rbegin();
    for(int ii = 0; ii < 3; ii++){
        std::cout << *it++ << std::endl;
    }
    
}