Ural_1654. Cipher Message(棧)

　　/*我太二了， 上來就暴力，然後TLE兩次。然後鬱悶的去吃飯，回來一想棧的結構，10分鐘AC。有種想撞牆的衝動！*/

//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;
}