Hello World!

題目描述
We know that Ivan gives Saya three problems to solve (Problem F), and this is the first problem.
“We need a programmer to help us for some projects. If you show us that you or one of your friends is able to program, you can pass the first hurdle.
I will give you a problem to solve. Since this is the first hurdle, it is very simple.”
We all know that the simplest program is the “Hello World!” program. This is a problem just as simple as the “Hello World!”
In a large matrix, there are some elements has been marked. For every marked element, return a marked element whose row and column are larger than the showed element’s row and column respectively. If there are multiple solutions, return the element whose row is the smallest; and if there are still multiple solutions, return the element whose column is the smallest. If there is no solution, return -1 -1.
Saya is not a programmer, so she comes to you for help

Can you solve this problem for her?

輸入
The input consists of several test cases.
The first line of input in each test case contains one integer N (0<N≤1000), which represents the number of marked element.
Each of the next N lines containing two integers r and c, represent the element’s row and column. You can assume that 0<r, c≤300. A marked element can be repeatedly showed.

The last case is followed by a line containing one zero.

輸出

For each case, print the case number (1, 2 …), and for each element’s row and column, output the result. Your output format should imitate the sample output. Print a blank line after each test case.

示例輸入
3
1 2
2 3
2 3

0

示例輸出
Case 1:
2 3
-1 -1

-1 -1

題意：有一個矩陣，輸入座標代表將矩陣某些位置標記，標記結束後，再重新查詢一遍，輸出比已經標記的比當前輸入的橫、縱座標都大的點。

注意：

先標記，所有標記完後再查詢。

找橫、縱座標都大的點。（任何一個相等都不行）

當然，排序不可少，但是如果用一個數組存，排序後，原先訪問順序就沒有了，所以最好兩個陣列存狀態。

#include <iostream>  
#include<string.h>  
#include<algorithm>  
using namespace std;  
  
struct point  
{  
    int x;  
    int y;  
};  
point p[1005];  
point p2[1005];  
int N;  
bool cmp(point a,point b)  
{  
    if(a.x==b.x)    return a.y<b.y;  
    else    return a.x<b.x;  
}  
  
void find(point p)  
{  
    int i;  
    if(p.x>p2[N-1].x && p.y>p2[N-1].y)  
    {  
        cout<<"-1 -1"<<endl;  
        return;  
    }  
  
    for(i=0;i<N;++i)  
    {  
        if(p2[i].x>p.x && p2[i].y>p.y)  
        {  
            cout<<p2[i].x<<" "<<p2[i].y<<endl;  
            return;  
        }  
    }  
    cout<<"-1 -1"<<endl;  
}  
  
int main()  
{  
    int count_case;  
    count_case = 1;  
    int i,j;  
    while(cin>>N&&N)  
    {  
        for(int i = 0;i<N;i++)  
            cin>>p[i].x>>p[i].y;  
        memcpy(p2,p,sizeof(p));  
  
        sort(p2,p2+N,cmp);  
  
        cout<<"Case "<<count_case++<<":"<<endl;  
        for(i = 0;i<N;i++)  
            find(p[i]);  
        cout<<endl;  
    }  
    return 0;  
}