贪心 CodeForces 124B Permutations

 1 /*
 2     贪心：全排列函数使用，更新最值
 3 */
 4 #include <cstdio>
 5 #include <algorithm>
 6 #include <cstring>
 7 #include <cmath>
 8 #include <string>
 9 #include <vector>
10 #include <map>
11 #include <set>
12 #include <iostream>
13 #include <queue>
14 using namespace std;
15 
16 typedef long long ll;
17 const int MAXN = 20;
18 const int INF = 0x3f3f3f3f;
19 int b[MAXN];
20 char a[MAXN][MAXN];
21 
22 int main(void)        //CodeForces 124B Permutations
23 {
24 //    freopen ("A.in", "r", stdin);
25 
26     int n, k;
27     while (scanf ("%d%d", &n, &k) == 2)
28     {
29         for (int i=1; i<=n; ++i)
30         {
31             scanf ("%s", a[i] + 1);
32         }
33         for (int i=1; i<=k; ++i)    b[i] = i;
34 
35         ll ans = INF;
36         do
37         {
38             ll mx = 0, mn = INF;    ll sum = 0;
39             for (int i=1; i<=n; ++i)
40             {
41                 sum = 0;
42                 for (int j=1; j<=k; ++j)
43                 {
44                     sum = sum * 10 + (a[i][b[j]] - '0');
45                 }
46                 if (sum > mx)    mx = sum;
47                 if (sum < mn)    mn = sum;
48             }
49             ans = min (ans, mx - mn);
50         }while (next_permutation (b+1, b+1+k));
51 
52         printf ("%I64d
", ans);
53     }
54 
55     return 0;
56 }
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