递推 Codeforces Round #186 (Div. 2) B. Ilya and Queries

题目传送门

 /*
     递推：用cnt记录前缀值，查询区间时，两个区间相减
 */
 #include <cstdio>
 #include <algorithm>
 #include <cmath>
 #include <cstring>
 using namespace std;

 const int MAXN = 1e5 + ;
 const int INF = 0x3f3f3f3f;
 char s[MAXN];
 int cnt[MAXN];

 int main(void)      //Codeforces Round #186 (Div. 2) B. Ilya and Queries
 {
     scanf ("%s", s + );
     int len = strlen (s + );

     memset (cnt, , sizeof (cnt));
     for (int i=; i<len; ++i)
     {
         cnt[i] = cnt[i-] + (s[i] == s[i+] ?  : );
 //        printf ("%d ", cnt[i]);
     }
     cnt[len] = cnt[len-];

     int m;    scanf ("%d", &m);
     while (m--)
     {
         int l, r;    scanf ("%d%d", &l, &r);
         printf ("%d\n", cnt[r-] - cnt[l-]);
     }

     return ;
 }