我全都要

 1 #include <bits/stdc++.h>
 2 #define ll long long
 3 using namespace std;
 4 const int N=1e5+10;
 5 string str;
 6 int n,k;
 7 unordered_map<char,int>rec,ans;
 8 bool judge(){
 9    for(int i=‘a‘;i<=‘z‘;i++){
10       int c=(char)i;
11       if(!rec[c]) continue;
12       if(ans[c]<k) return 0;
13    }
14    return 1;
15 }
16 bool check(int len){
17    ans.clear();
18    int l=0,r=len-1;
19    for(int i = l; i <= r; i++)
20       ans[str[i]]++;
21    while(r<n){
22       if(judge())
23          return true;
24       ans[str[l]]--;
25       l++;
26       r++;
27       if(r<n)
28        ans[str[r]]++;
29    }
30    return false;
31 }
32 
33 int main(){
34    ios::sync_with_stdio(0);
35    cin.tie(0);
36    cout.tie(0);
37    int t;
38    cin >> t;
39    while(t--){
40       rec.clear();
41       cin>>n>>k;
42       cin>>str;
43       if(!k) {
44          cout << "0" << endl;
45          continue;
46       }
47       for(int i = 0; i < n; i++){
48          rec[str[i]]++;
49       }
50       bool flag=1;
51       for(int i=‘a‘;i<=‘z‘;i++) {
52          int c=(char)i;
53          if (rec[c]>0 && rec[c]<k){
54             flag=0;
55             break;
56          }
57       }
58       if(flag) {
59          int l = 1, r = n;
60          while (l < r) {
61             int mid = l + r >> 1;
62             if (check(mid)) {
63                r=mid;
64             } else
65                l=mid+1;
66          }
67          cout<<l<<endl;
68       }
69       else
70          cout<<"-1"<<endl;
71    }
72 }