cf 762C. Two strings

因为要删去1个串（读错题），所以就直接二分搞就好了。

需要预处理出2个分别从头到尾，或从尾到头需要多长a串的数组，然后二分删去多长就好了。

 #include<bits/stdc++.h>
 #define LL long long
 #define N 100005
 #define lowbit(x) x&(-x)
 using namespace std;
 inline int ra()
 {
     int x=,f=; char ch=getchar();
     while (ch<'' || ch>'') {if (ch=='-') f=-; ch=getchar();}
     while (ch>='' && ch<='') {x=x*+ch-''; ch=getchar();}
     return x*f;
 }
 char a[N], b[N];
 int fl[N], fr[N];
 int la, lb, i, j, mid, l, r, a1, a2;
 int main()
 {
     scanf("%s%s",a+,b+);
     la=strlen(a+); lb=strlen(b+);
     for (i=,fl[]=j=; b[i]; i++)
     {
         for (j++; j<=la && a[j]!=b[i]; j++);
         fl[i]=j;
     }
     for (i=lb, fr[lb+]=j=la+; b[i]; i--)
     {
         for (j--; j> && a[j]!=b[i]; j--);
         fr[i]=j;
     }
     for (l=,r=lb; l<=r;)
     {
         mid=(l+r)>>;
         for (i=; i+mid<=lb; i++)
             if (fl[i]<fr[i+mid+]) break;
         if (i+mid<=lb) a1=i,a2=mid+i+,r=mid-;
         else l=mid+;
     }
     for (int i=; i<=a1; i++) putchar(b[i]);
     for (int i=a2; i<=lb; i++) putchar(b[i]);
     if (a2-a1>lb) putchar('-');
     return ;
 }