生成最短新闻摘要

问题描述和解题思路见此：http://www.cnblogs.com/flyinghearts/archive/2011/03/24/1994453.html。关于此问题我没什么好说的，值得一提的是请注意下面我的代码里那两个辅助函数：C++返回数组的长度；同时查找数组中的最大者和最小者。

#include<iostream>
#include<map>
#include<vector>
#include<algorithm>
#include<string>
#include<utility>   //pair

using namespace std;

const string message[]={ "微软","亚洲","研究院","成立","于","1998","年","，","我们","的","使命",
    "是","使","未来","的","计算机","能够","看","、","听","、","学","，",
    "能","用","自然语言","与","人类","进行","交流","。","在","此","基础","上",
    "，","微软","亚洲","研究院","还","将","促进","计算机","在","亚太","地区",
    "的","普及","，","改善","亚太","用户","的","计算","体验","。","”"};
const int MAX=65535;

//返回数组的长度
template<typename T,size_t N>
inline size_t getsz(T (&arr)[N]){　　　　//当参数是数组的引用时，数组长度对编译器是可见的
    return N;
}

//同时找出最小者和最大者
template<typename T>
inline pair<T,T> findMinAndMax(vector<T> arr){
    T min=MAX;
    T max=-1;
    int i=0;
    int N=arr.size();
    for(;i<N-1;i+=2){
        //一次读入两个数，小者与min比较，大者与max比较
        if(arr[i]<arr[i+1]){
            if(arr[i]<min)
                min=arr[i];
            if(arr[i+1]>max)
                max=arr[i+1];
        }else{
            if(arr[i+1]<min)
                min=arr[i+1];
            if(arr[i]>max)
                max=arr[i];
        }
    }
    if(i+1==N){
        if(arr[i]<min)
            min=arr[i];
        if(arr[i]>max)
            max=arr[i];
    }
    pair<T,T> p(min,max);
    return p;
}

int main(int argc,char *argv[]){
    //用户命令行输入关键字，存入map
    map<string,int> keywords;
    for(int i=1;i<argc;i++){
        keywords[argv[i]]=i;
    }
    //创建一个数组，记录每个关键词最近一次在消息中出现的位置
    vector<int> pos(argc-1);
    vector<int> spos(argc-1); //记录最短摘要对应的关键词在消息中出现的位置(下标从1开始)
    int slen=MAX;       //记录最短摘要的长度
    bool accur=false;   //标记所有关键词是否已经在消息中出现过
    //开始遍历消息
    int len=getsz(message);
    for(int i=0;i<len;i++){
        int p=keywords[message[i]];
        if(p==0)
            continue;
        pos[p-1]=i+1;
        if(accur==false){
            int mul=1;
            for(int j=0;j<argc-1;j++){
                mul*=pos[j];
                if(mul==0)
                    break;
            }
            if(mul!=0)
                accur=true;
        }
        if(accur==true){
            pair<int,int> p=findMinAndMax(pos);
            int ll=p.second=p.first;
            if(ll<slen){
                slen=ll;
                spos=pos;
            }
        }
    }
    //输出结果
    if(accur==false){
        cout<<"没有找到包含所有关键词的消息摘要"<<endl;
        return 0;
    }
    pair<int,int> p=findMinAndMax(spos);
    for(int i=p.first-1;i<=p.second-1;i++)
        cout<<message[i]<<" ";
    cout<<endl;

    return 0;
}