poj 3069

#include <stdio.h>#include <stdlib.h>int a[1010];int cmp(int *a,int *b){    return *a-*b;}int main(){    int R,n,i,j,k,count;;    while(scanf("%d%d",&R,&n)){        if(R==-1&&n==-1)break;        count=0;        for(i=0;i<n;i++)            scanf("%d",&a[i]);        qsort(a,n,sizeof(a[0]),cmp);        i=0;        while(i<n){            j=a[i++];            while(i<n&&a[i]<=j+R)i++;            k=a[i-1];            while(i<n&&a[i]<=k+R)i++;            count++;        }        printf("%d\n",count);    }    return 0;}

贪心水题。