【算法竞赛入门经典学习日记】第二章 循环结构程序设计

例题 数据统计（重定向，无bug版）

#include <iostream>
#include <cstdio>

int main()
{
freopen("infile","r","stdin");
freopen("outfile","w","stdout");
int x, min, max, n = 0, sum = 0,count = 0;
while(std::cin>>n && n)
{
count++;
int s =0;
cin>>x;
min = x; max = x;
for(int i = 1; i < n; i++)
{
std::cin>>x;
s += x;
if(x < min) min = x;
if(x > max) max = x;
}
std::cout<<"Case"<< count <<":"<< min <<" "<< max <<" "<< (double)s/n <<'\n';
}
return 0;
}

习题2-1 水仙花数

#include <iostream>

int main()
{
int i;
for(i = 100; i < 999; i++)
{
int j,k,l;
j = i/100;
k = i%100/10;
l = i%10;
if(j*j*j + k*k*k + l*l*l == i) std::cout<< i << std::endl;
//else continue;
}
return 0;
}

习题2-2 韩信点兵

#include <iostream>

int main()
{
int a,b,c,count = 0;
while(std::cin>>a>>b>>c)
{
int i;
count++;
for(i = 100; i <= 100; i++)
if(i%3 == a && i%5 == b && i%7 == c) break;
if(i < 100 | (100%3 == a && 100%5 == b && 100%7 == c))
std::cout<< "Case" << count << ":"  << i << std::endl;
else
std:: <<"Case"<< count << ":No answer" << srd::endl;;
}
return 0;
}

习题2-3 倒三角形

#include <iostream>
int main()
{
int i,j,k,n;
std::cin>> n;
for(i = n; i > 0; i--)
{
for(j = n-i; j > 0; j--) std::cout<<" ";
for(k = 2*i-1; k > 0; k--) std::cout<<  "#";
std::cout<<'\n';
}
return 0;
}

习题2-4 子序列的和

#include <iostream>
#include <cstdio>
int main()
{
int count = 0;
double a,b,sum = 0;
while(std::cin>>a>>b)
{
if(a == b && a == 0) break;
count++;
if(a > 100)      //当a大于100时，其平方倒数小于0.00001
{
std::cout<<"Case"<< count << ":" << 0.00001 << std::endl;
continue;
}
for(int i = b-a; i >= 0; i--)
sum += 1/((a+i)*(a+i));
std::cout<<"Case"<< count <<":";
printf("%.5f\n", sum);
}
return 0;
}

习题2-5 分数化小数

4000
[code]#include <iostream>
#include <iomanip>

int main()
{
int a,b,c,count = 0;
while(std::cin>>a>>b>>c)
{
if(a == 0 && b == 0 && c == 0) break;
count++;
std::cout.precision(c);
std::cout.setf(std::ios::fixed);  //设置小数位位数为c
std::cout<<"Case"<< count << (double)a/(double)b <<std::endl;
}
return 0;
}

习题2-6 排列

#include <iostream>

int main()
{
int i,j,k;
int a[9+1];
for(i = 123; i <= 329; i++)
{
int n;
j = 2 * i;
k = 3 * i;
a[i/100]++;
a[i%100/10]++;
a[i%10]++;
a[j/100]++;
a[j%100/10]++;
a[j%10]++;
a[k/100]++;
a[k%100/10]++;
a[k%10]++;
for(n = 1; n < 10; n++)
if(a
!= 1) break;
if(n > 9) std::cout<< i <<" "<< j <<" "<< k <<std::endl;
for(n = 0; n < 10; n++)
a
= 0;
}
return 0;
}