C++ CodeWar KATA4：Human readable duration format

让我们先来读题：

Your task in order to complete this Kata is to write a function which formats a duration, given as a number of seconds, in a human-friendly way.

The function must accept a non-negative integer. If it is zero, it just returns "now". Otherwise, the duration is expressed as a combination of years, days, hours, minutes and seconds.

It is much easier to understand with an example:

* For seconds = 62, your function should return "1 minute and 2 seconds"
* For seconds = 3662, your function should return"1 hour, 1 minute and 2 seconds"

其实理解起来很简单，给定你一个秒数，让你根据现实转换成年，日，小时，分钟，秒的组合。其中要注意标点符号以及"and"的顺序及位置。

做题思路：

首先将各个年月日的计算结果num放到一个vector中，再将各个计算结果对应的英语名称放到另一个vector<string>中。（注意顺序，应该是一一对应的）如果碰到num为0的情况，直接在遍历中continue即可，大于1的情况下，通过stringstream转换成string后再加's'即可。

通过观察可以发现"and"仅会出现一次，并且出现在倒数第二个非零的num所对应的时间跨度以及最后一个非零的num所对应的时间跨度中间。于是我写了一个get_vector_notzero函数用于数出每个num后续对应的非零num个数。其余情况都是", "。

下面请看代码。

#include <string>
#include <vector>
#include <algorithm>
#include <sstream>using namespace std;
int get_vector_notzero(vector<int>vec,int pos)//计算当前位置的num后面还有多少个非零数{ int count = 0;for(auto i =pos+1;i<vec.size();i++){if(vec[i]!=0) count +=1;}return count;}string format_duration(int seconds) {// your code herestringstream ss;//用于int和string类型的转换vector<int> num;vector<string> str1;vector<string> punc;//放置标点符号的vectorstring now = "now";string year = "year";str1.push_back(year);string day = "day";str1.push_back(day);string hour = "hour";str1.push_back(hour);string minute ="minute";str1.push_back(minute);string second ="second";str1.push_back(second);punc.push_back(", ");punc.push_back(" and ");string res;//存放结果的stringint Num_year,Num_day,Num_hour,Num_minute,Num_second;//计算所需的时间Num_year=seconds/31536000;num.push_back(Num_year);Num_day = (seconds-31536000*Num_year)/86400;num.push_back(Num_day);Num_hour = (seconds-31536000*Num_year-86400*Num_day)/3600;num.push_back(Num_hour);Num_minute = (seconds-31536000*Num_year-86400*Num_day-3600*Num_hour)/60;num.push_back(Num_minute);Num_second = seconds-31536000*Num_year-86400*Num_day-3600*Num_hour-60*Num_minute;num.push_back(Num_second);if(seconds==0) return now;else{for(auto i = 0;i<5;i++){if(num[i]==0) continue;else{string temp_str;if(num[i]>1) str1[i]+='s';//res+=num[i];ss<<num[i];ss>>temp_str;res+=temp_str;res+=" ";ss.clear();res+=str1[i];int vector_notzero = get_vector_notzero(num,i);if(i==4) break;//如果是最后一个数，直接跳出循环else if(vector_notzero==0) break;//如果后面的数都为0，无需加标点，直接退出循环else if(vector_notzero==1) //如果后面还有一个数不为0，那么加and{res+=punc[1];//1是and 0是”，“continue;}else res+=punc[0];}}return res;}
}