HDU 2209 翻纸牌游戏(DFS)

#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <cstring>
#include <stack>
#include <queue>
#include <algorithm>
#include <cmath>
#include <map>
#define PI 3.1415926
#define ms(a) memset(a,0,sizeof(a))
#define msp memset(mp,0,sizeof(mp))
#define msv memset(vis,0,sizeof(vis))
using namespace std;
//#define LOCAL
int a[120];
int ans;
int dfs(int i,int len,int cnt)
{
    if(i==len)
    {
        if(a[len-1])return 1e9;
        else return cnt;
    }
    if(a[i-1])a[i-1]=0,a[i]=!a[i],a[i+1]=!a[i+1],cnt++;
    return dfs(i+1,len,cnt);
}
int main()
{
#ifdef LOCAL
    freopen("in.txt", "r", stdin);
#endif // LOCAL
    ios::sync_with_stdio(false);
    char t[120];
    while(cin>>t)
    {
        int len=strlen(t);
        for(int i=0;i<len; i++)a[i]=t[i]-‘0‘;
        a[0]=!a[0],a[1]=!a[1];
        int ans=1e9;
        ans=min(dfs(1,len,1),ans);
        for(int i=0,len=strlen(t);i<len; i++)a[i]=t[i]-‘0‘;
        ans=min(dfs(1,len,0),ans);
        if(ans==1e9)printf("NO\n");
        else printf("%d\n",ans);
    }
    return 0;
}