Openjudge 1.4 逻辑表达式与条件分支

1.4.1

a==0！！！！！！！！！！
判断等于== 赋值符号=（注意！！！！）
#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;
int main( ){
	int a=0;
	scanf("%d",&a);
	if(a>0) {
		printf("positive");
	}
	if(a==0){
		printf("zero");
	}
	if(a<0){
		printf("negative");
	}
	return 0;} 

http://noi.openjudge.cn/ch0104/01/

1.4.4

读取单个字符 getchar() 速度更快
存放的是字符对应的ASCII码

#include<bits/stdc++.h>
using namespace std;
int main(){
	char ch;
	ch = getchar();
	if (ch%2 == 0) cout << "NO" << endl;
	else cout << "YES" << endl;
	return 0;
  }

1.4.14

#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;
int main()
{
    int weight,cost=8;
    char quick;
scanf("%d%s",&weight,&quick);
    if (weight > 1000) {
        weight -= 1000;
        cost += weight/500*4;
        if (weight%500 != 0) cost += 4;
    }
    if (quick == 'y') cost += 5;
    printf("%d",cost);
    return 0;
}

//字符串所对应的类型
//{%d int  %f float   %lf double %s char[]} %c单个字符

1.4.18

#include <iostream>
#include <cstdio>#include <cmath>using namespace std;int main(){
    int a,b,c;
    char k;
    scanf("%d %d",&a,&b);
    //scanf("",&b);
    scanf("%s",&k); 
    printf(" %d/ %d/",a,b);
    if(b==0&&k=='/'){
    	printf("Divided by zero!");
		return 0;
	}
	if(k!='+'&&k!='-'&&k!='/'&&k!='*'){
		printf("Invalid operator!");
		return 0;
	}
    if(k=='+'){
    	c=a+b;
		printf("%d",c);
    	return 0;
	};
	if(k=='-'){
		c=a-b;		
		printf("%d",c);
    	return 0;
	}
	if(k=='*'){
		c=a*b;		
		printf("%d",c);
    	return 0;
	}
	if(k=='/'){
		c=a/b;		
		printf("%d",c);
    	return 0;
	}}