洛谷P2882 [USACO07MAR]面对正确的方式Face The Right Way

#include <bits/stdc++.h>
#define For(i, j, k) for(int i=j; i<=k; i++)
#define Dow(i, j, k) for(int i=j; i>=k; i--)
#define LL long long
using namespace std;
inline int read() {
    int x = 0, f = 1;
    char ch = getchar();
    while(ch<'0'||ch>'9') { if(ch=='-') f = -1; ch = getchar(); }
    while(ch>='0'&&ch<='9') { x = x*10+ch-48; ch = getchar(); }
    return x * f;
}
void write(int x) {
    if(x<0) putchar('-'), x = -x;
    if(x>9) write(x/10);
    putchar(x%10+48);
}
inline void writeln(int x) { write(x); putchar('
'); }

const int N = 5011;
int n, ans, KK; 
int a[N], f[N]; 

int main() {
    n = read(); 
    For(i, 1, n) {
        char ch[5]; 
        scanf("%s", ch+1); 
        if(ch[1]=='B') a[i] = 1; 
    }
    
    ans = 1e9; 
    For(K, 1, n) {
        int t = 0, ok = 1, sum = 0; 
        For(i, 1, n) f[i] = 0;  
        For(i, 1, n-K+1) {
            if( (a[i]+t)%2==1 ) {
                ++f[i+K-1]; 
                ++t; 
                ++sum; 
            }
            t -= f[i]; 
            f[i] = 0; 
        }
        For(i, n-K+2, n) {
            if( (a[i]+t)%2==1 ) {
                ok = 0; 
                break; 
            }
            t -= f[i]; 
            f[i] = 0; 
        }
        if(ok && sum<ans) {
            KK = K; 
            ans = sum; 
        }
    }
    printf("%d %d
", KK, ans); 
}