Ural_1654. Cipher Message(栈)

　　/*我太二了， 上来就暴力，然后TLE两次。然后郁闷的去吃饭，回来一想栈的结构，10分钟AC。有种想撞墙的冲动！*/

//My Code:

#include <iostream>
#include <cstdio>
#include <cstring>

using namespace std;

const int N = 200005;

char s[N];
char str[N];

int main() {
    //freopen("data.in", "r", stdin);

    int len, top, i;
    while(cin.get(str, N) != NULL) {
        len =  strlen(str);
        top = 0;
        s[top++] = str[0];
        for(i = 1; i < len; i++) {
            if(str[i] != s[top-1]) {
                s[top++] = str[i];
            } else {
                top--;
            }
        }
        for(i = 0; i < top; i++)
            printf("%c", s[i]);
        printf("\n");
    }
    return 0;
}