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Icerain likes strings very much. Especially the strings only consist of 0 and 1,she call them easy strings. One day, she is so boring that she want to find how many good substrings in an easy string?
A good substring is a substring which can be a palindrome string after you change any two characters‘ positions(you can do this operation any times).For example,100 is a good substring of 1001,beacuse you can change it to be 010,which is a palindrome string.
The first line is the number of test cases. (no more than 100)
Each test case has one line containing one string only consist of 0 and 1. The length of the string is no greater than 100000.
For each test case, output one line contains the number of good substrings.
| Sample Input | Sample Output |
|---|---|
2 01 01101 |
2 11 |
解题报告
前缀dp...感谢卿神指导..
1 #include <iostream> 2 #include <cstring> 3 #include <algorithm> 4 using namespace std; 5 const int maxn = 1e5 + 5; 6 int dp[4]; 7 char buffer[maxn]; 8 9 int main(int argc,char *argv[]) 10 { 11 int Case; 12 scanf("%d",&Case); 13 while(Case--) 14 { 15 scanf("%s",buffer); 16 int len = strlen(buffer); 17 long long ans = 0; 18 memset(dp,0,sizeof(dp)); 19 for(int i = 1 ; i <= len ; ++ i) 20 { 21 int flag = 0; 22 if (buffer[i-1] == ‘1‘) 23 { 24 swap(dp[0],dp[1]); 25 swap(dp[2],dp[3]); 26 flag = 1; 27 } 28 else 29 { 30 swap(dp[0],dp[3]); 31 swap(dp[1],dp[2]); 32 } 33 if (flag) 34 dp[2] ++ ; 35 else 36 dp[0] ++ ; 37 ans += (dp[0] + dp[2] + dp[3]); 38 } 39 cout << ans << endl; 40 } 41 return 0; 42 }
UESTC_How many good substrings CDOJ 1026
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原文地址：http://www.cnblogs.com/Xiper/p/4467784.html
