[USACO11DEC]Umbrellas for Cows

嘟嘟嘟

我dp真是太弱了，这么简单dp都不会。

令dp[i]表示前 i 头牛头被遮住了的最低成本。则dp[i] = min{dp[i], dp[j - 1] + c[a[i] - a[j] + 1]} (1 <= j <= i)

然后别忘了预处理后缀最小值。

 #include<cstdio>
 #include<iostream>
 #include<cmath>
 #include<algorithm>
 #include<cstring>
 #include<cstdlib>
 #include<cctype>
 #include<vector>
 #include<stack>
 #include<queue>
 using namespace std;
 #define enter puts("")
 #define space putchar(' ')
 #define Mem(a, x) memset(a, x, sizeof(a))
 #define rg register
 typedef long long ll;
 typedef double db;
 const ll INF = 1e12;
 const db eps = 1e-;
 const int maxn = 5e3 + ;
 const int maxm = 1e5 + ;
 inline ll read()
 {
   ll ans = ;
   char ch = getchar(), last = ' ';
   while(!isdigit(ch)) last = ch, ch = getchar();
   while(isdigit(ch)) ans = (ans << ) + (ans << ) + ch - '', ch = getchar();
   if(last == '-') ans = -ans;
   return ans;
 }
 inline void write(ll x)
 {
   if(x < ) x = -x, putchar('-');
   if(x >= ) write(x / );
   putchar(x %  + '');
 }

 int n, m, a[maxn], c[maxm];
 ll dp[maxn];

 int main()
 {
   n = read(); m = read();
   for(int i = ; i <= n; ++i) a[i] = read();
   sort(a + , a + n + );
   for(int i = ; i <= m; ++i) c[i] = read();
   for(int i = m - ; i; --i) c[i] = min(c[i], c[i + ]);
   for(int i = ; i <= n; ++i) dp[i] = INF;
   for(int i = ; i <= n; ++i)
     for(int j = ; j <= i; ++j)
       dp[i] = min(dp[i], dp[j - ] + c[a[i] - a[j] + ]);
   write(dp[n]), enter;
   return ;
 }