基本算法，求交集

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一，交集运算算法

求多列数据的交集是一种应用广泛应用的算法，例如在搜索应用中，一个搜索关键词被分成了多个Term，每个Term对应一个倒排链表，那个整个搜索关键词的

搜索结果就是各个Term对应倒排链表元素的交集。

二，算法

/*************************************************************************    > File Name: intersection.cpp    > Author:zhangtx    > Mail: 18510665908@163.com    > Created Time: 2015年06月04日 星期四 17时19分17秒 ************************************************************************/#include <vector>#include<iostream>using namespace std;template<class T>void printResult(int left,int right,T data[]){    cout<<endl<<"**************************************************************"<<endl;    for(int idx=left;idx<=right;idx++)        cout<<data[idx]<<"   ";}template<class T>int partition(int left,int right,T data[]){    T tmpData=data[(left+right)/2];    data[(left+right)/2]=data[left];    data[left]=tmpData;    while(left<right)    {        while(data[right]>=tmpData && left<right) right--;        data[left]=data[right];        while(data[left]<=tmpData && left<right) left++;        data[right]=data[left];    }       data[left]=tmpData;    return left;}template<class T>void quickSort(int left,int right,T data[]){    if (left < right)    {        int pos=partition<int>(left,right,data);           quickSort(left,pos-1,data);        quickSort(pos+1,right,data);    }}template<class T>void intersection(int testData[][12],int column){    int *index=new int[column];    int *count=new int[column];    for (int idx=0;idx<column;idx++)    {        count[idx]=sizeof(testData[idx])/sizeof(int);        index[idx]=0;    }    int idx=0;    while(true)    {        T max=testData[0][index[0]];        /*get current max value of each array          * */        for(idx=0;idx<column;idx++)        {            if(testData[idx][index[idx]]>max)                max=testData[idx][index[idx]];        }        /*         * move pos according to max         * */        for(idx=0;idx<column;idx++)            while(testData[idx][index[idx]]<max && index[idx]<count[idx]) index[idx]++;        /*         * wheather the current value of each array is equal         * */        for(idx=0;idx<column-1;idx++)        {            if (testData[idx][index[idx]]!=testData[idx+1][index[idx+1]])                break;        }        if (idx==column-1)            cout<<max<<" ";        bool flag=false;        for(idx=0;idx<column;idx++)        {            if (index[idx]>count[idx])            {                /*                 * one array is over                 * */                flag=true;                break;            }            /*step to next*/            index[idx]++;        }        if (flag==true)            break;    }}int main(int argc,char *argv[]){    int testDataA[][12]={                          {53,5,7,19,12,324,46,76,928,111,2322,343},                          {53,51,7,19,12,3224,46,76,928,111,232,22},                          {53,51,7,19,12,3224,46,76,928,111,23222,11}                        };    //cout<<endl<<"sorting before"<<endl;    int countA=sizeof(testDataA[0])/sizeof(int);    //printResult<int>(0,countA-1,testDataA[0]);    quickSort<int>(0,countA-1,testDataA[0]);    cout<<endl<<"sorting result"<<endl;    printResult<int>(0,countA-1,testDataA[0]);    //cout<<endl<<"sorting before"<<endl;    int countB=sizeof(testDataA[1])/sizeof(int);    //printResult<int>(0,countB-1,testDataA[1]);    quickSort<int>(0,countB-1,testDataA[1]);    cout<<endl<<"sorting result"<<endl;    printResult<int>(0,countB-1,testDataA[1]);    //cout<<endl<<"sorting before"<<endl;    int countC=sizeof(testDataA[2])/sizeof(int);    //printResult<int>(0,countC-1,testDataA[2]);    quickSort<int>(0,countC-1,testDataA[2]);    cout<<endl<<"sorting result"<<endl;    printResult<int>(0,countC-1,testDataA[2]);    cout<<endl<<"intersection"<<endl;/* intersection algo*/    intersection<int>(testDataA,3);    cout<<endl;    return 0;}

三，运算

[root@M-192-168-10-225 algo]# g++ -g intersection.cpp [root@M-192-168-10-225 algo]# ./a.outsorting result**************************************************************5   7   12   19   46   53   76   111   324   343   928   2322   sorting result**************************************************************7   12   19   22   46   51   53   76   111   232   928   3224   sorting result**************************************************************7   11   12   19   46   51   53   76   111   928   3224   23222   intersection7 12 19 46 53 76 111 928

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