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

 

题目传送门

 1 /*  2  递推：用cnt记录前缀值，查询区间时，两个区间相减  3 */  4 #include <cstdio>  5 #include <algorithm>  6 #include <cmath>  7 #include <cstring>  8 using namespace std;  9 10 const int MAXN = 1e5 + 10; 11 const int INF = 0x3f3f3f3f; 12 char s[MAXN]; 13 int cnt[MAXN]; 14 15 int main(void) //Codeforces Round #186 (Div. 2) B. Ilya and Queries 16 { 17 scanf ("%s", s + 1); 18 int len = strlen (s + 1); 19 20 memset (cnt, 0, sizeof (cnt)); 21 for (int i=1; i<len; ++i) 22  { 23 cnt[i] = cnt[i-1] + (s[i] == s[i+1] ? 1 : 0); 24 // printf ("%d ", cnt[i]); 25  } 26 cnt[len] = cnt[len-1]; 27 28 int m; scanf ("%d", &m); 29 while (m--) 30  { 31 int l, r; scanf ("%d%d", &l, &r); 32 printf ("%d\n", cnt[r-1] - cnt[l-1]); 33  } 34 35 return 0; 36 }