CF:Ilya and Queries
2013-06-01 00:12
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Ilya the Lion wants to help all his friends with passing exams. They need to solve the following problem to pass the IT exam.
You've got string s = s1s2... sn (n is
the length of the string), consisting only of characters "." and "#"
and m queries. Each query is described by a pair of integers li, ri (1 ≤ li < ri ≤ n).
The answer to the query li, ri is
the number of such integers i (li ≤ i < ri),
that si = si + 1.
Ilya the Lion wants to help his friends but is there anyone to help him? Help Ilya, solve the problem.
Input
The first line contains string s of length n (2 ≤ n ≤ 105).
It is guaranteed that the given string only consists of characters "." and "#".
The next line contains integer m (1 ≤ m ≤ 105) —
the number of queries. Each of the next m lines contains the description of the corresponding query. The i-th
line contains integers li, ri (1 ≤ li < ri ≤ n).
Output
Print m integers — the answers to the queries in the order in which they are given in the input.
Sample test(s)
input
output
input
output
You've got string s = s1s2... sn (n is
the length of the string), consisting only of characters "." and "#"
and m queries. Each query is described by a pair of integers li, ri (1 ≤ li < ri ≤ n).
The answer to the query li, ri is
the number of such integers i (li ≤ i < ri),
that si = si + 1.
Ilya the Lion wants to help his friends but is there anyone to help him? Help Ilya, solve the problem.
Input
The first line contains string s of length n (2 ≤ n ≤ 105).
It is guaranteed that the given string only consists of characters "." and "#".
The next line contains integer m (1 ≤ m ≤ 105) —
the number of queries. Each of the next m lines contains the description of the corresponding query. The i-th
line contains integers li, ri (1 ≤ li < ri ≤ n).
Output
Print m integers — the answers to the queries in the order in which they are given in the input.
Sample test(s)
input
...... 4 3 4 2 3 1 6 2 6
output
1 1 5 4
input
#..### 5 1 3 5 6 1 5 3 6 3 4
output
1 1 2 2 0
解题报告:大概意思是先给出一个串s,然后给出m行,每行给出l,r两个数求满足s[i+1]==s[i];的个数.l<=i<r;
可以定义一个整形数组A【】;然后求出每一位之前符合要求的个数,当输入了l,r;时,A[r]-A[l]即为【l,r】之间符合的个数;
参考代码:
#include <stdio.h> #include<string.h> char str[100010]; int A[100010]; int main() { //freopen("in.txt","r",stdin); int i,n,m,j,k,t,a,b,s; scanf("%s",str); memset(A,0,sizeof(A)); scanf("%d ",&m); n=strlen(str); for(i=1;i<n;i++) {A[i]=A[i-1]+(str[i]==str[i-1]); } while(m--) { s=0; scanf("%d %d ",&a,&b); printf("%d\n",A[b-1]-A[a-1]); } return 0; }
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