直接DP一下就好了嘛、、、
首先对人数从大到小排序，然后f[i]表示的是人数为i的政党联盟能否成立
f[i] 由 f[i - a[now]]转移过来，同时保证i - a[now] <= sum即可
1 /************************************************************** 2 Problem: 1334 3 User: rausen 4 Language: C++ 5 Result: Accepted 6 Time:156 ms 7 Memory:1196 kb 8 ****************************************************************/ 9 10 #include <cstdio> 11 #include <algorithm> 12 13 using namespace std; 14 15 int n, sum, ans; 16 int a[305]; 17 int f[100005]; 18 19 int main() { 20 int i, j; 21 scanf("%d", &n); 22 for (i = 1; i <= n; ++i) 23 scanf("%d", a + i), sum += a[i]; 24 sort(a + 1, a + n + 1); 25 f[0] = 1; 26 for (i = n; i; --i) 27 for (j = sum / 2 + a[i]; j >= a[i]; --j) 28 if (f[j - a[i]]) 29 f[j] = 1, ans = max(j, ans); 30 printf("%d ", ans); 31 return 0; 32 }