HDU 4749 Parade Show(贪心+kmp)

题目链接

题目都看不懂，做毛线。。。看懂了之后就是kmp出，所有的匹配区间，然后DP可以写，贪心也可以做把，DP应该需要优化一下，直接贪，也应该对的，经典贪心问题。

 #include<iostream>
 #include<cstring>
 #include<cstdio>
 #include<cmath>
 #include<algorithm>
 using namespace std;
 int s1[],s2[];
 int p[],o[];
 int next[];
 int flag[];
 int judge(int x,int y)
 {
     if(x == y)
     return ;
     else if(x > y)
     return ;
     else
     return -;
 }
 int main()
 {
     int n,m,k,len1,len2,i,j;
     while(scanf("%d%d%d",&n,&m,&k)!=EOF)
     {
         memset(flag,,sizeof(flag));
         for(i = ;i < n;i ++)
         scanf("%d",&p[i]);
         for(i = ;i < m;i ++)
         scanf("%d",&o[i]);
         if(m == )
         {
             printf("%d\n",n);
             continue;
         }
         for(i = ;i < m-;i ++)
         s1[i] = judge(o[i+],o[i]);
         for(i = ;i < n-;i ++)
         s2[i] = judge(p[i+],p[i]);
         len1 = m-;//kmp
         len2 = n-;
         next[] = -;
         j = -;
         for(i = ;i < len1;i ++)
         {
             while(j >= &&s1[j+] != s1[i])
             j = next[j];
             if(s1[j+] == s1[i]) j ++;
             next[i] = j;
         }
         j = -;
         for(i = ;i < len2;i ++)
         {
             while(j >= &&s1[j+] != s2[i])
             j = next[j];
             if(s1[j+] == s2[i])j ++;
             if(j == len1-)
             {
                 flag[i-len1+] = ;
                 j = next[j];
             }
         }
         int ans = ;
         for(i = ;i < n-;i ++)
         {
             if(flag[i])
             {
                 ans ++;
                 i = i + m - ;
             }
         }
         printf("%d\n",ans);
     }
     return ;
 }