UVA 105 solution C++ Code

#include<stdio.h>

int main(){
    int a[20001],i,l,r,pv,h,max,f;
    for(i=0;i<20000;i++)
    a[i]=0;max=0;
    while(scanf("%d%d%d",&l,&h,&r)!=EOF){
        if(l==-1)break;
        for(i=l;i<r;i++){
            if(a[i]<h)a[i]=h;
            if(r>max)max=r;
        }
}

       for(i=0,pv=0,f=1;i<=max+1;i++){
           if(pv!=a[i]){
           pv=a[i];
           if(f){printf("%d %d",i,pv);f=0;}
           else printf(" %d %d",i,pv);}
       }
       printf("\n");


 return 0;
}