排序,二分检索,从最大的开始找~~就OK啦。。注意goto跳出循环哦·
#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,会超时滴...
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; 学习一下
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;
}