算法竞赛入门经典第二版习题答案

fprintf(fout,\fclose(fin); fclose(fout); //system(\return 0;

}

2-1(freopen)

#include

//#define LOCAL// 在编译选项中定义 LOCAL int main()

#ifdef LOCAL freopen(\#endif

int a,i=0; scanf(\while(1)

{

a/=10;

i++; if(a<1)break;

}

}

printf(\

2-2(freopen)

#include //#define LOCAL// 编译选项中定义 int main()

{

#ifdef LOCAL freopen(\#endif

int a,b,c,m; for(a=1;a<=9;a++)

{

for(b=0;b<=9;b++)

{

for (c=0;c<=9;c++)

{ m=a*100+b*10+c; if(m==a*a*a+b*b*b+c*c*c)printf(\

}

} }

//system(\

return 0;

}

2-2(fin)

#include int main()

{

FILE *fout; fout=fopen(\int a,b,c,m;

for(a=1;a<=9;a++)

{

for(b=0;b<=9;b++)

{

for(c=0;c<=9;c++)

{

m=a*a*a+b*b*b+c*c*c; if(m==a*100+b*10+c) fprintf(fout,\

}

}

}

fclose(fout);

{

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return 0;

}

2-3(fin)

#include int main()

{

FILE *fin,*fout;

fin=fopen(\fout=fopen(\//fin=stdin; //fout=stdout;

int a,b,c,x,temp=0;//temp 用来判断是否在 10 到 100 内存在这样的数 fscanf(fin,\for(x=10;x<=100;x++)

{

if(x%3==a&&x%5==b&&x%7==c)

{

fprintf(fout,\temp=1; break;

} }

if(!temp)fprintf(fout,\fclose(fin); fclose(fout); return 0;

}

2-3(freopen)

#include int main()

{

// 会在编译选项中定义 LOCAL #ifdef LOCAL

freopen(\#endif

int a,b,c,x,temp=0;

scanf(\for(x=10;x<=100;x++)

{

if(x%3==a&&x%5==b&&x%7==c)

{

printf(\temp=1; break;

}

}

if(!temp)printf(\return 0;

}

2-4(fin)

#include int main()

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{

FILE *fin,*fout;

fin=fopen(\fout=fopen(\//fin=stdin; //fout=stdout; int n,i,j,k;

fscanf(fin,\for(i=1;i<=n;i++)

{

for(j=1;j

for(k=-2*i+2*n+1;k>=1;k--)fprintf(fout,\

}

fclose(fin); fclose(fout); return 0;

}

2-4(freopen)

#include int main()

{

// 在编译选项内定义 LOCAL

#ifdef LOCAL freopen(\#endif

int n,i,j,k; scanf(\

{

for(j=1;j

}

}

return 0;

2-5(fin) #include int main()

{

FILE *fin,*fout; fin=fopen(\for(i=1;i<=n+1;i++) {

fscanf(fin,\

}

fclose(fin);

fin=fopen(\

{

fscanf(fin,\{

if(a

}

}

fclose(fin); fout=fopen(\

fclose(fout); return 0;

}

2-5(freopen) #include int main()

{

freopen(\freopen(\

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int n,a,i,m,count=0; scanf(\for(i=1;i<=n+1;i++)

{

scanf(\

}

freopen(\for(i=0;i<=n;i++)

{

scanf(\if(i!=0)

{

if(a

}

}

printf(\return 0;

}

2-6(fin)

#include int main()

{

FILE *fin,*fout;

fin=fopen(\int n,i; double H=0; fscanf(fin,\for(i=1;i<=n;i++)

{

H+=(double)1/i;

}

fclose(fin);

fout=fopen(\fclose(fout); return 0;

}

2-6(freopen) #include int main()

{

#ifdef LOCAL freopen(\#endif

int n,i; double H=0;

scanf(\{ H=H+double/i;

} printf(\

}

2-7(fin) #include int main()

{

FILE *fout; int i;

double H=0; for(i=1;2*i-1<1000000;i++) {

if(i%2==1)H+=(double)1/(2*i-1); else H-=(double)1/(2*i-1);

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}

fout=fopen(\return 0; }

2-7(freopen) #include int main()

{

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