A题
1 s = sum(map(int, raw_input().split()))
2 print s / 5 if s % 5 == 0 and s / 5 else -1
Ｂ题
1 n, m = map(int, raw_input().split())
2 div, lft = n / m, n % m;
3 mi = (div + 1) * (div) / 2 * lft + (div) * (div - 1) / 2 * (m - lft);
4 print mi, (n - m + 1) * (n - m) / 2
Ｃ题
1 a = map(int, raw_input().split())
2 a.sort()
3 print a[0] + a[1] if (a[0] + a[1]) * 2 <= a[2] else sum(a) / 3
Ｄ题
1 /*************************************************************************
2 > File Name: D.cpp
3 > Author: Stomach_ache
4 > Mail: sudaweitong@gmail.com
5 > Created Time: 2014年10月17日 星期五 21时39分21秒
6 > Propose:
7 ************************************************************************/
8 #include <cmath>
9 #include <string>
10 #include <cstdio>
11 #include <fstream>
12 #include <cstring>
13 #include <iostream>
14 #include <algorithm>
15 using namespace std;
16 /*Let's fight!!!*/
17
18 const int MOD = 1e9 + 7;
19 const int MAX_N = 200050;
20 int dp[MAX_N];
21
22 int main(void) {
23 ios_base::sync_with_stdio(false);
24 int r, g;
25 cin >> r >> g;
26 int h = 1;
27 while (h * (h + 1) / 2 <= r + g) h++;
28 h--;
29
30 memset(dp, 0, sizeof(dp));
31 dp[0] = 1;
32 for (int i = 1; i <= h; i++) {
33 for (int j = r; j >= i; j--) {
34 dp[j] = (dp[j] + dp[j - i]) % MOD;
35 }
36 }
37 h = h * (h + 1) / 2;
38 int res = 0;
39 for (int i = 0; i <= r; i++) if (i + g >= h) res = (res + dp[i]) % MOD;
40 cout << res << endl;
41
42 return 0;
43 }