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 ;

 }