codeforces 363C

原题链接

C. Fixing Typos

time limit per test1 second
memory limit per test256 megabytes
inputstandard input
outputstandard output
Many modern text editors automatically check the spelling of the user's text. Some editors even suggest how to correct typos.

In this problem your task to implement a small functionality to correct two types of typos in a word. We will assume that three identical letters together is a typo (for example, word "helllo" contains a typo). Besides, a couple of identical letters immediately followed by another couple of identical letters is a typo too (for example, words "helloo" and "wwaatt" contain typos).

Write a code that deletes the minimum number of letters from a word, correcting described typos in the word. You are allowed to delete letters from both ends and from the middle of the word.

Input
The single line of the input contains word s, its length is from 1 to 200000 characters. The given word s consists of lowercase English letters.

Output
Print such word t that it doesn't contain any typos described in the problem statement and is obtained from s by deleting the least number of letters.

If there are multiple solutions, print any of them.

Examples
input
helloo
output
hello
input
woooooow
output
woow
Note
The second valid answer to the test from the statement is "heloo".

注：一开始写用了标记数组，比较麻烦，而且一直有错误，后来学习了个简单的法子：单个遍历，符合条件就另入一个字符数组

#include <iostream>#include <cstdio>#include <cstring>using namespace std;char s1[200005],s2[200005];int main(){ int i,cnt=0; scanf("%s",s1); s2[0]=s1[0]; s2[1]=s1[1]; cnt=2; for(i=2;s1[i];i++) { if(cnt-2>=0&&s2[cnt-1]==s2[cnt-2]&&s2[cnt-2]==s1[i])//注意，现在遍历到的s1字符一定要和s2中字符比较（s1中字符已经有删除的了—） continue; if(cnt-3>=0&&s2[cnt-3]==s2[cnt-2]&&s2[cnt-1]==s1[i]) continue; s2[cnt++]=s1[i]; } printf("%s\n",s2); return 0;} </cstring></cstdio></iostream>