【HDOJ】3480 Division

斜率dp+滚动数组。

 /* 3480 */
 #include <iostream>
 #include <sstream>
 #include <string>
 #include <map>
 #include <queue>
 #include <set>
 #include <stack>
 #include <vector>
 #include <deque>
 #include <algorithm>
 #include <cstdio>
 #include <cmath>
 #include <ctime>
 #include <cstring>
 #include <climits>
 #include <cctype>
 #include <cassert>
 #include <functional>
 #include <iterator>
 #include <iomanip>
 using namespace std;
 //#pragma comment(linker,"/STACK:102400000,1024000")

 #define sti                set<int>
 #define stpii            set<pair<int, int> >
 #define mpii            map<int,int>
 #define vi                vector<int>
 #define pii                pair<int,int>
 #define vpii            vector<pair<int,int> >
 #define rep(i, a, n)     for (int i=a;i<n;++i)
 #define per(i, a, n)     for (int i=n-1;i>=a;--i)
 #define clr                clear
 #define pb                 push_back
 #define mp                 make_pair
 #define fir                first
 #define sec                second
 #define all(x)             (x).begin(),(x).end()
 #define SZ(x)             ((int)(x).size())
 #define lson            l, mid, rt<<1
 #define rson            mid+1, r, rt<<1|1

 const int maxn = ;
 const int maxm = ;
 int dp[][maxn];
 int Q[maxn];
 int a[maxn];
 int n, m;

 void solve() {
     int l, r;
     int p = , q = ;

     rep(i, , n+)
         dp[p][i] = (a[i] - a[]) * (a[i] - a[]);

     rep(i, , m+) {
         l = r = ;
         Q[r++] = i-;
         rep(j, i, n+) {
             while (l+ < r) {
                 int k1 = Q[l];
                 int k2 = Q[l+];
                 int x1 = a[k1+];
                 int x2 = a[k2+];
                 int y1 = dp[p][k1] + x1 * x1;
                 int y2 = dp[p][k2] + x2 * x2;
                 if ((y2-y1)<=*a[j]*(x2-x1))
                     ++l;
                 else
                     break;
             }
             int k = Q[l];
             int x = a[k+];
             dp[q][j] = dp[p][k] + (a[j]-x)*(a[j]-x);
             while (l+ < r) {
                 int k1 = j;
                 int k2 = Q[r-];
                 int k3 = Q[r-];
                 int x1 = a[k1+];
                 int x2 = a[k2+];
                 int x3 = a[k3+];
                 int y1 = dp[p][k1] + x1 * x1;
                 int y2 = dp[p][k2] + x2 * x2;
                 int y3 = dp[p][k3] + x3 * x3;
                 if ((y3-y2)*(x2-x1) >= (y2-y1)*(x3-x2))
                     --r;
                 else
                     break;
             }
             Q[r++] = j;
             #ifndef ONLINE_JUDGE
                 printf("l = %d, r = %d\n", l, r);
             #endif
         }
         q = p;
         p ^= ;
     }

     int ans = dp[p][n];
     printf("%d\n", ans);
 }

 int main() {
     ios::sync_with_stdio(false);
     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     int t;

     scanf("%d", &t);
     rep(tt, , t+) {
         scanf("%d %d", &n, &m);
         rep(i, , n+)
             scanf("%d", &a[i]);
         sort(a+, a++n);
         printf("Case %d: ", tt);
         solve();
     }

     #ifndef ONLINE_JUDGE
         printf("time = %d.\n", (int)clock());
     #endif

     return ;
 }