智乃的密码

https://ac.nowcoder.com/acm/contest/23478/I
#include<bits/stdc++.h>

using namespace std;

const int N = 1e4 + 10;
const int mod = 1e9 + 7;
typedef long long ll;

int n, m, L, R;
string s;
int pre[N][5];
int get (char ch) {
    if (ch >= 'a' && ch <= 'z') return 2;
    else if (ch >= 'A' && ch <= 'Z') return 1;
    else if (ch >= '0' && ch <= '9') return 3;
    else return 4;
}
bool ck (map<int, int> cnt) {
    int kind = 0;
    for (int i =1 ; i <= 4; i ++)
        if (cnt[i]) kind ++;
    return kind >= 3;
}
void solve() {
   cin >> n >> L >> R;
   cin >> s;
   map<int, int> cnt;
   ll ans = 0;
   for (int i = 0, j = i; i < n; i ++) {
       while (j <= n && !ck(cnt)) {
            if (j < n)
            cnt[get(s[j])] ++;
            j ++;
      }
      int l = max(j, i + L );
      int r = min(n, i + R );
      ans += max(r - l + 1, 0);
      cnt[get(s[i])] --;
   }
   cout << ans << endl;
} 
int main () {
   int t;
   t = 1;
   while (t --) solve();
   return 0;
} 

读题错误。单调性分析不对 如果[i, j]已经满足条件，那么[i, j + ...]一定满足条件就不需要继续下去了