河南第六届ACM省赛（外星人的供给站）

来源：互联网发布：mac显示两个窗口编辑：程序博客网时间：2024/04/28 17:34

题目地址：http://acm.nyist.net/JudgeOnline/problem.php?pid=710

思路：POJ1328原题，没想到把变量定义成int类型，按double类型使用会导致re,头一次遇到这种情况

#include <iostream>#include <cstdio>#include <cstdlib>#include <algorithm>#include <queue>#include <stack>#include <map>#include <cstring>#include <climits>#include <cmath>#include <cctype>const int inf = 0x7f7f7f7f;//2139062143typedef long long ll;using namespace std;struct point{    double left;    double right;};bool cmp(point a,point b){    return a.left < b.left;}int main(){    int t;    int n;    double r;    point a[110];    scanf("%d",&t);    while(t--)    {        scanf("%d%lf",&n,&r);        double x,y;//刚开始把x,y定义成int类型的，结果老是re        for(int i=0; i<n; i++)        {            scanf("%lf%lf",&x,&y);            a[i].left = x - sqrt(r*r-y*y);            a[i].right = x + sqrt(r*r-y*y);        }        sort(a,a+n,cmp);        double k = a[0].right;        int sum = 1;        for(int i=1; i<n; i++)        {            if(a[i].left > k)            {                sum++;                k = a[i].right;            }            else if(a[i].right < k)//左右都在上一个点的边界之内，所以要更新右边界            {                k = a[i].right;            }        }        printf("%d\n",sum);    }    return 0;}

我这个代码的错误是通过原点来判断，这样其实有很多错误，假如前一个点高一点，后面一个点低一点，这个圆的圆心应该要更新，我的却没有更新

错误代码：

#include <iostream>#include <cstdio>#include <cstdlib>#include <algorithm>#include <queue>#include <stack>#include <map>#include <cstring>#include <climits>#include <cmath>#include <cctype>const int inf = 0x7f7f7f7f;//2139062143typedef long long ll;using namespace std;struct point{    double x;    double y;};bool cmp(point a,point b){    return a.x < b.x;}int main(){    int t;    int n;    double r;    scanf("%d",&t);    point a[110];    while(t--)    {        scanf("%d%lf",&n,&r);        for(int i=0; i<n; i++)        {            scanf("%lf%lf",&a[i].x,&a[i].y);        }        sort(a,a+n,cmp);        double temp = sqrt(r*r-a[0].y*a[0].y);        temp += a[0].x;//求出第一个点的圆心        //printf("%lf\n",temp);        int sum = 1;        for(int i=1; i<n; i++)        {            double temp1 = sqrt(r*r-a[i].y*a[i].y);            temp1 = a[i].x - temp1;            //printf("%lf\n",temp1);            if(temp1 <= temp)            {                continue;            }            temp = temp1;            sum++;        }        printf("%d\n",sum);    }    return 0;}

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