1_04

辽宁师范大学 • 张大为@https://daweizh.github.io/noip/

1.4 编程基础之逻辑表达式与条件分支(21)

判断数正负，http://noi.openjudge.cn/ch0104/01/[+]

#include <iostream>
using namespace std;

int main(){
    int n;
    cin >> n;
    string s = "positive";
    if (n ==0)	
        s = "zero";
    else if (n<0)
        s = "negative";
    cout << s << endl;
          
    return 0;
}

输出绝对值，http://noi.openjudge.cn/ch0104/02/[+]

#include <iostream>
using namespace std;

int main(){
    double n;
    cin >> n;
    if (n<0)
        n = -n;
    printf("%.2f",n);
    
    return 0;
}

奇偶数判断，http://noi.openjudge.cn/ch0104/03/[+]

#include <iostream>
using namespace std;

int main(){
    int n;
    cin >> n;
    string s = "even";
    if (n%2==1)
        s = "odd";
    cout << s << endl;
    
    return 0;
}

奇偶ASCII值判断，http://noi.openjudge.cn/ch0104/04/[+]

#include <iostream>
using namespace std;

int main(){
    char c=getchar();
    string s = "NO";
    if (c%2==1)
        s = "YES";
    cout << s << endl;
    
    return 0;
}

整数大小比较，http://noi.openjudge.cn/ch0104/05/[+]

#include <iostream>
using namespace std;

int main(){
    int x,y;

    cin >> x >> y;
    string s = ">";
    if (x==y)
        s = "=";
    else if (x <y)
        s = "<"; 
    cout << s << endl;
    
    return 0;
}

判断是否为两位数，http://noi.openjudge.cn/ch0104/06/[+]

#include <iostream>
using namespace std;

int main(){
    int i;

    cin >> i;
    if (i>=10 && i<=99)
        i = 1;
    else
        i = 0;		
    cout << i << endl;
    
    return 0;
}

收集瓶盖赢大奖，http://noi.openjudge.cn/ch0104/07/[+]

#include <iostream>
using namespace std;

int main(){
    int x,y,z;

    cin >> x >> y;
    if (x>=10 || y >= 20)
        z = 1;
    else
        z = 0;		
    cout << z << endl;
    
    return 0;
}

判断一个数能否同时被3和5整除，http://noi.openjudge.cn/ch0104/08/[+]

#include <iostream>
using namespace std;

int main(){
  int n;

  cin >> n;
  string s = "NO";
  if (n % 3==0 && n % 5==0)
      s = "YES";
  cout << s << endl;
  
  return 0;
}

判断能否被3，5，7整除，http://noi.openjudge.cn/ch0104/09/[+]

#include <iostream>
using namespace std;

int main(){
    int a; 
    
    cin >> a ;
    if(a%3==0 && a%5==0 && a%7==0){
        cout << 3 << " " << 5 << " " << 7 << endl;
    }else if(a%3==0 && a%5==0){
        cout << 3 << " " << 5 << endl;
    }else if(a%5==0 && a%7==0){
        cout << 5 << " " << 7 << endl;
    }else if(a%3==0 && a%7==0){
        cout << 3 << " " << 7 << endl;
    }else if(a%3==0){
        cout << 3 << endl;
    }else if(a%5==0){
        cout << 5 << endl;
    }else if(a%7==0){
        cout << 7 << endl;
    }else{
        cout << "n" << endl;
    }
    
    return 0;
}

有一门课不及格的学生，http://noi.openjudge.cn/ch0104/10/[+]

#include <iostream>
using namespace std;

int main(){
    int c1,c2;

    cin >> c1 >> c2;
    string s = "0";
    if ((c1<60 && c2>=60 )|| (c1>=60 && c2 <60))
        s = "1";
    cout << s << endl;
    
    return 0;
}

晶晶赴约会，http://noi.openjudge.cn/ch0104/11/[+]

#include <iostream>
using namespace std;

int main(){
    int d;

    cin >> d;
    string s = "YES";
    if (d==1 || d==3 || d == 5 )
        s = "NO";
    cout << s << endl;
    
    return 0;
}

骑车与走路，http://noi.openjudge.cn/ch0104/12/[+]

#include <iostream>
using namespace std;

int main(){
    double m;

    cin >> m;
    string s = "All";
    double bikeTime = m / 3.0 + 50;
    double walkTime = m / 1.2;
    if ( bikeTime < walkTime )
        s = "Bike";
    else if (bikeTime > walkTime)
        s = "Walk";
    cout << s << endl;
    
    return 0;
}

分段函数，http://noi.openjudge.cn/ch0104/13/[+]

#include <iostream>
using namespace std;

int main(){
    double n,f=0;

    cin >> n;
    if ( n>=0 && n < 5 )
        f = -n + 2.5;
    else if (n>=5 && n<10)
        f = 2 -1.5*(n-3)*(n-3);
    else if (n>=10 && n<20)
        f = n / 2 - 1.5;
    printf("%.3f",f);
    
    return 0;
}

计算邮资，http://noi.openjudge.cn/ch0104/14/[+]

#include <iostream>
#include <cmath>
using namespace std;

int main(){
    double w;
    char c;
    int f;

    cin >> w >> c;
    if (w <= 1000)
        f = 8;
    else
        f = ceil((w-1000)/500)*4 + 8;
    if (c=='y')
        f = f + 5;
    printf("%d",f);
    
    return 0;
}

最大数输出，http://noi.openjudge.cn/ch0104/15/[+]

#include <iostream>
using namespace std;

int main(){
    int a,b,c;

    cin >> a >> b >> c;
    if(a>b && b>c){
        cout << a << endl;
    }else if(b>c){
        cout << b << endl;
    }else{
        cout << c << endl; 
    }
    
    return 0;
}

三角形判断，http://noi.openjudge.cn/ch0104/16/[+]

#include <iostream>
using namespace std;

int main(){
    int x,y,z;
    
    cin >> x >> y >>z;
    string s = "yes";
    if (x + y <= z)
        s = "no";
    else if(x + z <= y)
        s = "no";
    else if(y + z <= x)				
        s = "no";
    cout << s << endl;
    
    return 0;
}

判断闰年，http://noi.openjudge.cn/ch0104/17/[+]

#include <iostream>
using namespace std;

int main(){
    int y;

    cin >> y;
    string s = "N";
    if (y % 4 ==0 && !(y % 100==0 && y % 400 !=0) && !(y%3200==0))
        s = "Y";
    cout << s << endl;
    
    return 0;
}

点和正方形的关系，http://noi.openjudge.cn/ch0104/18/[+]

#include <iostream>
using namespace std;

int main(){
    int x,y;

    cin >>x >> y;
    string s = "no";
    if (x<=1 && x>=-1 && y <=1 && y>=-1)
        s = "yes";
    cout << s << endl;
    
    return 0;
}

简单计算器，http://noi.openjudge.cn/ch0104/19/[+]

#include <iostream>
using namespace std;

int main(){
    int x,y;
    char c;
    int result = 0;
    string s = "";

    cin >>x >> y >> c;
    switch(c){
        case '+':
            result = x + y;
            break;
        case '-':
            result = x - y;
            break;
        case '*':
            result = x * y;
            break;
        case '/':
            if (y==0)
                s = "Divided by zero!";
            else
                result = x / y;
            break;
        default:
            s = "Invalid operator!";		
    }	
    if (s=="")
        cout << result << endl;
    else
        cout << s << endl;
    
    return 0;
}

求一元二次方程的根，http://noi.openjudge.cn/ch0104/20/[+]

#include <iostream>
#include <cmath>
using namespace std;

int main(){
    double a,b,c;

    cin >> a >> b >> c;
    double b2 = b * b;
    double dt = 4 * a * c;
    double a2 = 2 * a;
    if (b2 < dt){
        double r = -b / a2;
        if (b==0){
            r = 0;
        }
        double v = sqrt(dt-b2)/a2;
        printf("x1=%.5f+%.5fi;x2=%.5f-%.5fi",r,v,r,v);
    }else{
        double x1 = (-b + sqrt(b2-dt))/a2;
        double x2 = (-b - sqrt(b2-dt))/a2;
        if (b2>dt){
            printf("x1=%.5f;x2=%.5f",x1,x2);
        }else{
            printf("x1=x2=%.5f",x1);
        }
    }

    return 0;		
}

苹果和虫子2，http://noi.openjudge.cn/ch0104/21/[+]

#include <iostream>
using namespace std;

int main(){
    int n;  //苹果数量 
    int x;  //虫子吃一个苹果花的时间 
    int y; 	//虫子吃了多少时间的苹果
    
    cin >> n>> x >>y;  //分别输入苹果个数，虫子吃一个苹果的时间，虫子吃了多长时间的苹果 
    if(n>0){ 	//如果箱子里有苹果 
        if(x>0){
            if(y>0){
                int m = y/x; //计算吃了几个整苹果
                if(y%x!=0)
                    m = m + 1;
                if(n-m>0)
                    cout << n-m << endl;
                else
                    cout << "0" << endl;
            }else{
              cout << n << endl;
            }
        }else{
          cout << n << endl;
        }
    }else{ 		//否则，箱子里没有苹果 
        cout << "0" << endl;
    }
    
    return 0;
}

参考网址

http://noi.openjudge.cn