简单选择

#include <stdio.h>
int main(){
    int n,i,sum;
    float GPA;
    while(scanf("%d",&n)!=EOF){
        float a[n],b[n];
        GPA=0;
        sum=0;
        for(i=0;i<n;i++) scanf("%f ",&a[i]);
        for(i=0;i<n;i++) scanf("%f ",&b[i]);
        for(i=0;i<n;i++) sum+=a[i];
        for(i=0;i<n;i++) {
            if(b[i]>=90) b[i]=4.0;
            else if(b[i]>=85) b[i]=3.7;
            else if(b[i]>=82) b[i]=3.3;
            else if(b[i]>=78) b[i]=3.0;
            else if(b[i]>=75) b[i]=2.7;
            else if(b[i]>=72) b[i]=2.3;
            else if(b[i]>=68) b[i]=2.0;
            else if(b[i]>=64) b[i]=1.5;
            else if(b[i]>=60) b[i]=1.0;
            else  b[i]=0;
        }
        for(i=0;i<n;i++)
            GPA+=a[i]*b[i];
        GPA/=sum;
        printf("%.2f\n",GPA);
    }
}