%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：

  1 #define IOS ios_base::sync_with_stdio(0); cin.tie(0);
  2 #include <cstdio>//sprintf islower isupper
  3 #include <cstdlib>//malloc  exit strcat itoa system("cls")
  4 #include <iostream>//pair
  5 #include <fstream>
  6 #include <bitset>
  7 //#include <map>
  8 //#include<unordered_map>
  9 #include <vector>
 10 #include <stack>
 11 #include <set>
 12 #include <string.h>//strstr substr
 13 #include <string>
 14 #include <time.h>//srand(((unsigned)time(NULL))); Seed n=rand()%10 - 0~9;
 15 #include <cmath>
 16 #include <deque>
 17 #include <queue>//priority_queue<long long, vector<long long>, greater<long long> > q;//less
 18 #include <vector>//emplace_back
 19 //#include <math.h>
 20 //#include <windows.h>//reverse(a,a+len);// ~ ! ~ ! floor
 21 #include <algorithm>//sort + unique : sz=unique(b+1,b+n+1)-(b+1);+nth_element(first, nth, last, compare)
 22 using namespace std;//next_permutation(a+1,a+1+n);//prev_permutation
 23 #define fo(a,b,c) for(register long long a=b;a<=c;++a)
 24 #define fr(a,b,c) for(register long long a=b;a>=c;--a)
 25 #define mem(a,b) memset(a,b,sizeof(a))
 26 #define pr printf
 27 #define sc scanf
 28 void swapp(long long &a,long long &b);
 29 double fabss(double a);
 30 long long maxx(long long a,long long b);
 31 long long minn(long long a,long long b);
 32 long long Del_bit_1(long long n);
 33 long long lowbit(long long n);
 34 long long abss(long long a);
 35 //const long long INF=(1LL<<60);
 36 const double E=2.718281828;
 37 const double PI=acos(-1.0);
 38 const long long inf=(1<<29);
 39 const double ESP=1e-9;
 40 const long long mod=(long long)1e9+7;
 41 const long long N=(long long)1e6+6;
 42  
 43 char s[N];
 44 long long ans=0;
 45  
 46 int main()
 47 {
 48     sc("%s",s+1);
 49     s[0]='&';
 50     long long l=strlen(s)-1;
 51     long long cont=0;
 52     long long cnt[4]={0,0,0,0},temp=0;
 53     fr(i,l,1)
 54     {
 55         temp+=s[i]-'0';
 56         temp%=3;
 57         cnt[temp]++;
 58         if(s[i]=='0')
 59             cont++;
 60     }
 61     fr(i,l,1)
 62     {
 63         if(s[i]==s[i+1]&&s[i]=='0')
 64         ans+=cnt[0];
 65         temp=s[i]-'0';
 66         temp%=3;
 67         if(temp==0)
 68             cnt[0]--;
 69         else if(temp==1)
 70         {
 71             long long a=cnt[2],b=cnt[1],c=cnt[0];
 72             cnt[0]=b-1;cnt[1]=a,cnt[2]=c;
 73         }
 74         else
 75         {
 76             long long a=cnt[2],b=cnt[1],c=cnt[0];
 77             cnt[0]=a-1,cnt[1]=c,cnt[2]=b;
 78         }
 79     }
 80  
 81     pr("%lld\n",ans+cont);
 82     return 0;
 83 }
 84  
 85 /**************************************************************************************/
 86  
 87 long long maxx(long long a,long long b)
 88 {
 89     return a>b?a:b;
 90 }
 91  
 92 void swapp(long long &a,long long &b)
 93 {
 94     a^=b^=a^=b;
 95 }
 96  
 97 long long lowbit(long long n)
 98 {
 99     return n&(-n);
100 }
101  
102 long long Del_bit_1(long long n)
103 {
104     return n&(n-1);
105 }
106  
107 long long abss(long long a)
108 {
109     return a>0?a:-a;
110 }
111  
112 double fabss(double a)
113 {
114     return a>0?a:-a;
115 }
116  
117 long long minn(long long a,long long b)
118 {
119     return a<b?a:b;
120 }

 

posted @ 2019-08-30 21:57  ZMWLxh  阅读(258)  评论(0)  编辑  收藏  举报