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C. Hometask
Sergey attends lessons of the N-ish language. Each lesson he receives a hometask. This time the task is to translate some sentence to the N-ish language. Sentences of the N-ish language can be represented as strings consisting of lowercase Latin letters without spaces or punctuation marks.
Sergey totally forgot about the task until half an hour before the next lesson and hastily scribbled something down. But then he recollected that in the last lesson he learned the grammar of N-ish. The spelling rules state that N-ish contains some "forbidden" pairs of letters: such letters can never occur in a sentence next to each other. Also, the order of the letters doesn‘t matter (for example, if the pair of letters "ab" is forbidden, then any occurrences of substrings "ab" and "ba" are also forbidden). Also, each pair has different letters and each letter occurs in no more than one forbidden pair.
Now Sergey wants to correct his sentence so that it doesn‘t contain any "forbidden" pairs of letters that stand next to each other. However, he is running out of time, so he decided to simply cross out some letters from the sentence. What smallest number of letters will he have to cross out? When a letter is crossed out, it is "removed" so that the letters to its left and right (if they existed), become neighboring. For example, if we cross out the first letter from the string "aba", we get the string "ba", and if we cross out the second letter, we get "aa".
The first line contains a non-empty string s, consisting of lowercase Latin letters — that‘s the initial sentence in N-ish, written by Sergey. The length of string s doesn‘t exceed 105.
The next line contains integer k (0 ≤ k ≤ 13) — the number of forbidden pairs of letters.
Next k lines contain descriptions of forbidden pairs of letters. Each line contains exactly two different lowercase Latin letters without separators that represent the forbidden pairs. It is guaranteed that each letter is included in no more than one pair.
Print the single number — the smallest number of letters that need to be removed to get a string without any forbidden pairs of neighboring letters. Please note that the answer always exists as it is always possible to remove all letters.
ababa
1
ab
2
codeforces
2
do
cs
1
贪心
题目自身限制每个字母最多出现在一个限制词语中，给出k个限制词语，将问题转化为k个子问题，对每个限制词语遍历给出的字符串，如限制词do，若出现连续的oddoood(连续的o和d)，统计o和d出现的次数，消去较小的次数。
#include<cstdio> #include<cstring> using namespace std; const int N=100005; char fb[14][2]; char s[N]; int main() { int n; gets(s); scanf("%d\n",&n); int len=strlen(s); for(int i=1;i<=n;i++) { scanf("%c%c",&fb[i][0],&fb[i][1]); getchar(); } int cnt=0,cntt=0,res=0; for(int j=1;j<=n;j++) { cnt=0,cntt=0; for(int i=0;i<len;i++) { if(s[i]==fb[j][0] || s[i]==fb[j][1]) { if(s[i]==fb[j][0]) cnt++; else if(s[i]==fb[j][1]) cntt++; } else { res+=min(cnt,cntt); cnt=cntt=0; } } if(s[len-1]==fb[j][0] || s[len-1]==fb[j][1]) res+=min(cnt,cntt); } printf("%d\n",res); return 0; }
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原文地址：http://www.cnblogs.com/LinesYao/p/5689556.html
