hdu 题目2034（水题），2036（水，简单计算多边形面积）,2037(水，贪心，会场安排类)

http://acm.hdu.edu.cn/showproblem.php?pid=2034

#include<stdio.h>
#include<iostream>
#include<string.h>
#include<algorithm>
using namespace std;
int a[110],c[110],n,mark[110];

int find(int b){
	for(int i=0;i<n;i++){
		if(a[i]==b) return i;
	}
	return -1;
}
int main()
{
	int j,k,cnt,m,i,b;
	while(scanf("%d%d",&n,&m),n||m){
		
		memset(mark,0,sizeof(mark));
		
		for(i=0;i<n;i++)
			scanf("%d",&a[i]);
			
		for(i=cnt=0;i<m;i++){
			scanf("%d",&b);
			k = find(b);
	//		cout<<k<<endl;
			if(k>=0){
				mark[k]=1;
				cnt++;
			}
		}
		if(n==cnt)puts("NULL");
		else{
			for(i=j=0;i<n;i++)
				if(!mark[i]) c[j++] = a[i];
			sort(c,c+j);
			for(i=0;i<j;i++)
				printf("%d ",c[i]);
			puts("");
		}
	}
	return 0;
}

http://acm.hdu.edu.cn/showproblem.php?pid=2036点击打开链接

http://blog.csdn.net/hpu_zyh/article/details/9920197点击打开链接计算多边形面积

#include <stdio.h>

struct point{
	int x,y;
}p[105];

double cross(point a,point b){
	return a.x*b.y - a.y*b.x; 
}
int main()
{
	int n,i;double sum;
	while(scanf("%d",&n),n){
		for(i=0;i<n;i++){
			scanf("%d%d",&p[i].x,&p[i].y);
		}
		sum=0;
		for(i=0;i<n-1;i++){
			sum += cross(p[i],p[i+1]);
		}
		sum += cross(p[n-1],p[0]);
		sum /= 2.0;
		printf("%.1lf\n",sum>0?sum:-sum);
	}
	return 0;
} 

http://acm.hdu.edu.cn/showproblem.php?pid=2037

#include<stdio.h>
#include<iostream>
#include<string.h>
#include<algorithm>
using namespace std;
struct match{
	int s,e;
}a[105];
bool cmp(match i,match j){
	return i.e<j.e;
}
int main()
{
	int cnt,n,i,last;
	while(scanf("%d",&n),n){
			
		for(i=0;i<n;i++)	scanf("%d%d",&a[i].s,&a[i].e);
		sort(a,a+n,cmp);
//		for(i=0;i<n;i++)	printf("i=%d,s=%d,e=%d\n",i,a[i].s,a[i].e);
		last = a[0].e;
		for(cnt=i=1;i<n;i++){
			if(a[i].s>=last){	cnt++;	last = a[i].e;	} 
		}
		printf("%d\n",cnt);
	}
	return 0;
}