Making the Grade [POJ3666] [DP]

 1 #include<set>
 2 #include<map>
 3 #include<queue>
 4 #include<stack>
 5 #include<cmath>
 6 #include<cstdio>
 7 #include<cstring>
 8 #include<iostream>
 9 #include<algorithm>
10 #define RG register ll
11 #define rep(i,a,b)    for(RG i=a;i<=b;++i)
12 #define per(i,a,b)    for(RG i=a;i>=b;--i)
13 #define ll long long
14 #define inf (1<<30)
15 #define maxn 2005
16 using namespace std;
17 ll n;
18 ll a[maxn],b[maxn],dp[maxn][maxn];
19 inline ll read()
20 {
21     ll x=0,f=1;char c=getchar();
22     while(c<‘0‘||c>‘9‘){if(c==‘-‘)f=-1;c=getchar();}
23     while(c>=‘0‘&&c<=‘9‘){x=x*10+c-‘0‘;c=getchar();}
24     return x*f;
25 }
26 
27 void work()
28 {
29     rep(i,1,n)
30     {
31         ll mn=inf;
32         rep(j,1,n)
33         {
34             mn=min(mn,dp[i-1][j]);
35             dp[i][j]=(a[i]-b[j]>=0?a[i]-b[j]:b[j]-a[i])+mn;
36         }
37     }
38     ll ans=inf;
39     rep(i,1,n) ans=min(ans,dp[n][i]);
40     cout<<ans;
41 }
42 
43 int main()
44 {
45     n=read();
46     rep(i,1,n) a[i]=b[i]=read();
47     sort(b+1,b+1+n);
48     work();
49     return 0;
50 }