51Nod 1127 最短的包含字符串 (尺取法)

 1 #include <iostream>
 2 #include <algorithm>
 3 #include <string>
 4 #include <cstring>
 5 
 6 #define INF 0xfffffff
 7 using namespace std;
 8 const int maxn = 26;
 9 int a[maxn];
10 
11 bool is_ok(){
12     for (int i = 0; i < 26; i++){
13         if (!a[i])
14             return false;
15     }
16     return true;
17 }
18 
19 int main(){
20     ios::sync_with_stdio(false);
21     string s;
22     cin >> s;
23     memset(a, 0, sizeof(a));
24     bool flag = true;
25     a[s[0] - 'A']++;
26     int ans = INF;
27     int l = 0;
28     for (int i = 1; i < s.length(); i++){
29         a[s[i] - 'A']++;
30         while (is_ok())
31         {
32             ans = min(ans, i - l + 1);
33             a[s[l++] - 'A']--;
34         }
35     }
36     if (ans == INF){
37         cout << "No Solution" << endl;
38     }
39     else
40         cout << ans << endl;
41     system("pause");
42     return 0;
43 }