以下是AC的程序，朴素的方法：

/*
Program		:	The Average
Author		:	Chen Mingcheng
*/

#include <iostream>
#include <iomanip>
#include <cstdio>

using namespace std;

const int maxn = 100;

int big[maxn], small[maxn];
int n1, n2, n, l1, l2;

inline void Swap(int &a, int &b) {
	int temp = a;
	a = b;
	b = temp;
}

void Solve() {
	__int64 sum = 0;
	l1 = l2 = 0;
	int i, j, x;
	for (i = 0; i < n; i++) {
		scanf("%d", &x);
		sum += x;
		big[l1++] = x;
		j = l1 - 1;
		for (; j > 0 && big[j] > big[j - 1]; j--)
			Swap(big[j], big[j - 1]);
		small[l2++] = x;
		j = l2 - 1;
		for (; j > 0 && small[j] < small[j - 1]; j--)
			Swap(small[j], small[j - 1]);
		if (l1 > n1) l1--;
		if (l2 > n2) l2--;
	}
	for (i = 0; i < l1; i++)
		sum -= big[i];
	for (i = 0; i < l2; i++)
		sum -= small[i];
	long double ans = (long double)sum;
	ans /= (long double)(n - n1 - n2);
	cout << setiosflags(ios::fixed) << setprecision(6) << ans << endl;
}

int main() {
	while (1) {
		scanf("%d %d %d", &n1, &n2, &n);
		if (n1 == 0 && n2 == 0 && n == 0) break;
		Solve();
	}
	return 0;
}

以下是WA的程序，用了<set>
/*
Program		:	The Average
Author		:	Chen Mingcheng
*/

#include <iostream>
#include <iomanip>
#include <cstdio>
#include <set>

using namespace std;

set<int> seq1, seq2;
int n1, n2, n;

void Solve() {
	seq1.clear();
	seq2.clear();
	int i, x;
	__int64 sum = 0;
	long double ans;
	for (i = 0; i < n; i++) {
		scanf("%d", &x);
		sum += x;
		seq1.insert(-x);
		if (seq1.size() > n1) seq1.erase(--seq1.end());
		seq2.insert(x);
		if (seq2.size() > n2) seq2.erase(--seq2.end());
	}
	set<int>::iterator p;
	for (p = seq1.begin(); p != seq1.end(); p++)
		sum += *p;
	for (p = seq2.begin(); p != seq2.end(); p++)
		sum -= *p;
	ans = (long double)sum;
	ans /= (long double)(n - n1 - n2);
	cout << setiosflags(ios::fixed) << setprecision(6) << ans << endl;
}

int main() {
	while (1) {
		scanf("%d %d %d", &n1, &n2, &n);
		if (n1 == 0 && n2 == 0 && n == 0) break;
		Solve();
	}
	return 0;
}

• 应该用multiset (2271) frkstyc 2006-05-28 20:12:33
  • 多谢指点！ (0) cmc_hope 2006-05-28 20:15:43
• Set中不允许相同元素,multiset中允许存在相同的元素 (2271) sunmoonstar 2006-05-28 20:41:29
• Re:这题我的两个程序在数据类型使用上完全一样，为什么一个AC，一个WA？请管理员指教。 (2291) 200609020331 2009-01-06 13:36:23