#include
#include
#include
#include
#include
#include
#include
#include
#include
using?namespace?std;

const?int?ITERM_SIZE=1682;
const?int?USER_SIZE=943;
const?int?V=15;????????//ITERM的最近鄰居數(shù)
const?int?S=10;????????//USER的最近鄰居數(shù)

struct?MyPair{
????int?id;
????double?value;
????MyPair（int?i=0double?v=0）:id（i）value（v）{}
};

struct?cmp{
????bool?operator（）?（const?MyPair?&?obj1const?MyPair?&?obj2）const{
????????return?obj1.value?????}
};

double?rate[USER_SIZE][ITERM_SIZE];????//評(píng)分矩陣
MyPair?nbi[ITERM_SIZE][V];????????????//存放每個(gè)ITERM的最近鄰居
MyPair?nbu[USER_SIZE][S];????????????//存放每個(gè)USER的最近鄰居
double?rate_avg[USER_SIZE];????????????//每個(gè)用戶的平均評(píng)分

//從文件中讀入評(píng)分矩陣
int?readRate（string?filename）{
????ifstream?ifs;
????ifs.open（filename.c_str（））;
????if（!ifs）{
????????cout<<“error:unable?to?open?input?file?“<????????return?-1;
????}
????string?line;
????while（getline（ifsline））{
????????string?str1str2str3;
????????istringstream?strstm（line）;
????????strstm>>str1>>str2>>str3;
????????int?userid=atoi（str1.c_str（））;
????????int?itermid=atoi（str2.c_str（））;
????????double?rating=atof（str3.c_str（））;
		//cout?<		//break;
????????rate[userid-1][itermid-1]=rating;
????????line.clear（）;
????}
????ifs.close（）;
????return?0;
}

//計(jì)算每個(gè)用戶的平均評(píng)分
void?getAvgRate（）{
????for（int?i=0;i????????double?sum=0;
????????for（int?j=0;j????????????sum+=rate[i][j];
????????rate_avg[i]=sum/ITERM_SIZE;
????}
}

//計(jì)算兩個(gè)向量的皮爾森相關(guān)系數(shù)
double?getSim（const?vector?&vec1const?vector?&vec2）{
????int?len=vec1.size（）;
????assert（len==vec2.size（））;
????double?sum1=0;
????double?sum2=0;
????double?sum1_1=0;
????double?sum2_2=0;
????double?sum=0;
????for（int?i=0;i????????sum+=vec1[i]*vec2[i];
????????sum1+=vec1[i];
????????sum2+=vec2[i];
????????sum1_1+=vec1[i]*vec1[i];
????????sum2_2+=vec2[i]*vec2[i];
????}
????double?ex=sum1/len;
????double?ey=sum2/len;
????double?ex2=sum1_1/len;
????double?ey2=sum2_2/len;
????double?exy=sum/len;
????double?sdx=sqrt（ex2-ex*ex）;
????double?sdy=sqrt（ey2-ey*ey）;
????assert（sdx!=0?&&?sdy!=0）;
????double?sim=（exy-ex*ey）/（sdx*sdy）;
????return?sim;
}

//計(jì)算每個(gè)ITERM的最近鄰
void?getNBI（）{
????for（int?i=0;i????????vector?vec1;
????????priority_queuecmp>?neighbour;
????????for（int?k=0;k????????????vec1.push_back（rate[k][i]）;
????????for（int?j=0;j????????????if（i==j）
????????????????continue;
????????????vector?vec2;
????????????for（int?k=0;k????????????????ve