CF1043CSmallest Word（构造）

Posted 2021-01-16 myx12345

题意：给定一个由a和b构成的字符串，可以选择翻转或不翻转他的每个前缀，翻转记为1不翻转记为0，求能将字符串排序的字典序最小的操作序列

n<=1e3

思路：考虑极长的一段a [t,w]

翻转t-1与w就能把这段a移到最前面

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<string>
 4 #include<cmath>
 5 #include<iostream>
 6 #include<algorithm>
 7 #include<map>
 8 #include<queue>
 9 #include<vector>
10 #include<ctime>
11 using namespace std;
12 typedef long long ll;
13 typedef unsigned int uint;
14 typedef unsigned long long ull;
15 typedef pair<int,int> PII;
16 typedef vector<int> VI;
17 #define fi first
18 #define se second 
19 #define MP make_pair
20 #define N  210000
21 #define M  130
22 #define MOD 1000000007
23 #define eps 1e-8 
24 #define pi acos(-1)
25 
26 char a[N];
27 int b[N],c[N];
28 
29 int main()
30 {
31     scanf("%s",a+1);
32     int n=strlen(a+1);
33     for(int i=1;i<=n;i++)
34      if(a[i]==‘a‘) c[i]=0;
35       else c[i]=1;
36       
37     int i=0;
38     memset(b,0,sizeof(b));
39     while(i<=n)
40     {
41         i++;
42         if(c[i]==1||i>n) continue;
43         int t=i;
44         int w=i;
45         while(i+1<=n&&c[i+1]==0){i++; w++;}
46         b[t-1]^=1; b[w]^=1;
47     }
48     for(int i=1;i<=n-1;i++) printf("%d ",b[i]);
49     printf("%d",b[n]);
50     return 0;