zoj 1101 Gamblers

排序，二分檢索，從最大的開始找~~就OK啦。。注意goto跳出循環哦·

#include <stdio.h>
#include <stdlib.h>
#include <iostream>   
#include <string.h>   
#include <algorithm>
using namespace std; 
int n;
int wager[1020];
int BinarySearch(long long x)                                 
{
	int a,b,mid;
	a = 0;                                           
	b = n - 1;
	while(a <= b)                                    
	{
		mid = (a + b)/2;                          //若在while前，會超時滴... 
		
		if (x == wager[mid])                             
		{
			return mid;
		}
		if (x > wager[mid])                                
		{
			a = mid+1;
		}
		else                                          
		{
			b = mid-1;
		}
	}
	return(-1);                                        
}
int main()
{
	
	
	int i,j,k,sum,p;
	while(scanf("%d", &n) !=EOF)
    {
		if (n < 4) 
		{
			printf("no solution\n");
			continue;
		}
		
			for (i=0; i<n; i++)
			{
				scanf("%d", &wager[i]);
			}
			
			sort(wager,wager+n);                     //include<algorithm>   using namespace std; 學習一下        
			for (i=n-1; i>=0; i--)
			{
				for (j=n-1; j>=0; j--)
				{
					if ( i== j ) 
					{
						continue;
					}
				
					for (k=n-1; k>=0; k--)
					{
						if (k == i || k == j)
						{
							continue;
						}
						sum = wager[i] - wager[j]- wager[k];
						if( sum != wager[i] && sum != wager[j] && sum != wager[k] )
						{
							p = BinarySearch(sum);
							if (p!=-1)
							{
								printf("%d\n",wager[i]);
								goto exit;
					   	 	}
						}
					}
				}
			}
		
		
		printf("no solution\n");
		exit:;
	}
	
	return 0;
}