我们可以把AB看成S，则要找的串可以写成SSSSA或者SSSSS。假设S出现了Q次，那么A出现了Q % k次，则B出现了 Q / k - Q % k次.
当ABABA是SSS的形式时，B可以为空字符，判断Q / k - Q % k>=0。
当ABABA是SSA的形式时，判断Q / k - Q % k > 0。
1 #include<cstdio> 2 #include<iostream> 3 #include<algorithm> 4 #include<cmath> 5 #include<cstring> 6 #include<cstdlib> 7 #include<cctype> 8 #include<stack> 9 #include<queue> 10 #include<vector> 11 using namespace std; 12 #define enter puts("") 13 #define space putchar(' ') 14 #define Mem(a, x) memset(a, x, sizeof(a)) 15 #define rg register 16 typedef long long ll; 17 typedef double db; 18 const int INF = 0x3f3f3f3f; 19 const db eps = 1e-8; 20 const int maxn = 1e6 + 5; 21 inline ll read() 22 { 23 ll ans = 0; 24 char ch = getchar(), las = ' '; 25 while(!isdigit(ch)) las = ch, ch = getchar(); 26 while(isdigit(ch)) ans = ans * 10 + ch - '0', ch = getchar(); 27 if(las == '-') ans = -ans; 28 return ans; 29 } 30 inline void write(ll x) 31 { 32 if(x < 0) putchar('-'), x = -x; 33 if(x >= 10) write(x / 10); 34 putchar(x % 10 + '0'); 35 } 36 37 int n, k; 38 char s[maxn]; 39 int f[maxn]; 40 41 void init() 42 { 43 for(int i = 2, j = 0; i <= n; ++i) 44 { 45 while(j && s[j + 1] != s[i]) j = f[j]; 46 if(s[j + 1] == s[i]) j++; 47 f[i] = j; 48 } 49 } 50 51 bool work(int i, int cir) 52 { 53 int x = i / cir; 54 if(i % cir) return x / k > x % k; 55 else return x / k >= x % k; 56 } 57 58 int main() 59 { 60 n = read(), k = read(); 61 scanf("%s", s + 1); 62 init(); 63 for(int i = 1; i <= n; ++i) write(work(i, i - f[i])); 64 enter; 65 return 0; 66 }