哈夫曼编码

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cstdlib>
 5 #include <algorithm>
 6 #include <queue>
 7 #include <vector>
 8 #include <stack>
 9 #include <map>
10 #include <set>
11 #include <cmath>
12 #include <cctype>
13 #include <ctime>
14 
15 using namespace std;
16 
17 #define REP(i, n) for (int i = 0; i < (n); ++i)
18 #define eps 1e-9
19 #define SZ(x) ((int)x.size())
20 #define PI acos(-1.0)
21 #define lc id << 1
22 #define rc id << 1 | 1
23 #define lson low, mid, lc
24 #define rson mid + 1, high, rc
25 
26 typedef long long ll;
27 typedef unsigned long long ull;
28 typedef pair<int, int> pii;
29 const int maxn = 1e3;
30 char str[maxn];
31 int T, n, len;
32 int cnt[maxn];
33 multiset<int> s;
34 
35 int huffman(char* str, int len, int k) { //k表示进制数
36     s.clear(); memset(cnt, 0, sizeof(cnt)); int ret = 0, t;
37     for (int i = 0; i < len; ++i) { ++cnt[str[i]]; }
38     for (int i = 0; i < 200; ++i) {
39         if (cnt[i]) { s.insert(cnt[i]); }
40     }
41     if ((int)s.size() == 1) { return *s.begin(); }
42     while ((int)s.size() > 1) {
43         t = 0;
44         for (int i = 0; i < k; ++i) {
45             t += *s.begin(); s.erase(s.begin());
46         }
47         s.insert(t); ret += t;
48     }
49     return ret;
50 }
51 
52 int main() {
53 #ifdef __AiR_H
54     freopen("in.txt", "r", stdin);
55 //    freopen("out.txt", "w", stdout);
56 #endif // __AiR_H
57     scanf("%d", &T);
58     while (T--) {
59         scanf("%d %s", &n, str);
60         len = strlen(str); int ans = huffman(str, len, 2);
61         if (ans > n) { printf("no\n"); }
62         else { printf("yes\n"); }
63     }
64     return 0;
65 }