%300为0的个数（牛客第四场）-- number

题意：

给你一串数，问你如题。

思路：

我不是这样的作法，从后往前，先取00，再算%3==0的个数，往前推的时候有递推关系：

 #define IOS ios_base::sync_with_stdio(0); cin.tie(0);
 #include <cstdio>//sprintf islower isupper
 #include <cstdlib>//malloc  exit strcat itoa system("cls")
 #include <iostream>//pair
 #include <fstream>
 #include <bitset>
 //#include <map>
 //#include<unordered_map>
 #include <vector>
 #include <stack>
 #include <set>
 #include <string.h>//strstr substr
 #include <string>
 #include <time.h>//srand(((unsigned)time(NULL))); Seed n=rand()%10 - 0~9;
 #include <cmath>
 #include <deque>
 #include <queue>//priority_queue<long long, vector<long long>, greater<long long> > q;//less
 #include <vector>//emplace_back
 //#include <math.h>
 //#include <windows.h>//reverse(a,a+len);// ~ ! ~ ! floor
 #include <algorithm>//sort + unique : sz=unique(b+1,b+n+1)-(b+1);+nth_element(first, nth, last, compare)
 using namespace std;//next_permutation(a+1,a+1+n);//prev_permutation
 #define fo(a,b,c) for(register long long a=b;a<=c;++a)
 #define fr(a,b,c) for(register long long a=b;a>=c;--a)
 #define mem(a,b) memset(a,b,sizeof(a))
 #define pr printf
 #define sc scanf
 void swapp(long long &a,long long &b);
 double fabss(double a);
 long long maxx(long long a,long long b);
 long long minn(long long a,long long b);
 long long Del_bit_1(long long n);
 long long lowbit(long long n);
 long long abss(long long a);
 //const long long INF=(1LL<<60);
 const double E=2.718281828;
 const double PI=acos(-1.0);
 const long long inf=(<<);
 const double ESP=1e-;
 const long long mod=(long long)1e9+;
 const long long N=(long long)1e6+;

 char s[N];
 long long ans=;

 int main()
 {
     sc("%s",s+);
     s[]='&';
     long long l=strlen(s)-;
     long long cont=;
     long long cnt[]={,,,},temp=;
     fr(i,l,)
     {
         temp+=s[i]-'';
         temp%=;
         cnt[temp]++;
         if(s[i]=='')
             cont++;
     }
     fr(i,l,)
     {
         if(s[i]==s[i+]&&s[i]=='')
         ans+=cnt[];
         temp=s[i]-'';
         temp%=;
         if(temp==)
             cnt[]--;
         else if(temp==)
         {
             long long a=cnt[],b=cnt[],c=cnt[];
             cnt[]=b-;cnt[]=a,cnt[]=c;
         }
         else
         {
             long long a=cnt[],b=cnt[],c=cnt[];
             cnt[]=a-,cnt[]=c,cnt[]=b;
         }
     }

     pr("%lld\n",ans+cont);
     return ;
 }

 /**************************************************************************************/

 long long maxx(long long a,long long b)
 {
     return a>b?a:b;
 }

 void swapp(long long &a,long long &b)
 {
     a^=b^=a^=b;
 }

 long long lowbit(long long n)
 {
     return n&(-n);
 }

 long long Del_bit_1(long long n)
 {
     return n&(n-);
 }

 long long abss(long long a)
 {
     return a>?a:-a;
 }

 double fabss(double a)
 {
     return a>?a:-a;
 }

 long long minn(long long a,long long b)
 {
     return a<b?a:b;
 }