【HDOJ】4261 Estimation

挺不错的一道题，基本思路是dp。关键点是如何求区间内的Sigma|A_i-B_i|。
线段树做TLE了，优先队列可以过。

/* 4261 */
#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 INF = 1e9;
const int maxn = 2005;
const int maxm = 30;
int n, m;
int a[maxn];
int dp[maxm][maxn];
int dif[maxn][maxn];

void solve() {
    int tmp;
    
    rep(i, 1, n+1) {
        priority_queue<int> q;
        priority_queue<int, vi, greater<int> > Q;
        
        int ls, rs;
        int ln, rn;
        int x, xx;
        int l = 0;
        
        ln = rn = 0;
        ls = rs = 0;
        rep(j, i, n+1) {
            ++l;
            x = a[j];
            if (l & 1) {
                ++ln;
                if (rn && Q.top()<x) {
                    xx = Q.top();
                    Q.pop();
                    q.push(xx);
                    ls += xx;
                    Q.push(x);
                    rs += x - xx;
                } else {
                    q.push(x);
                    ls += x;
                }
                
                x = q.top();
                tmp = rs - ls + x;
                dif[i][j] = tmp;
            } else {
                ++rn;
                if (q.top() > x) {
                    xx = q.top();
                    q.pop();
                    Q.push(xx);
                    rs += xx;
                    q.push(x);
                    ls += x - xx;
                } else {
                    Q.push(x);
                    rs += x;
                }
                
                x = q.top();
                tmp = rs - ls;
                dif[i][j] = tmp;
            }
        }
    }
    
    rep(j, 1, n+1) {
        dp[1][j] = dif[1][j];
    }
    
    rep(i, 2, m+1) {
        rep(j, i, n+1) {
            dp[i][j] = INF;
            rep(k, i-1, j) {
                dp[i][j] = min(dp[i][j], dp[i-1][k]+dif[k+1][j]);
            }
        }
    }
    
    printf("%d
", dp[m][n]);
}

int main() {
    ios::sync_with_stdio(false);
    #ifndef ONLINE_JUDGE
        freopen("data.in", "r", stdin);
        freopen("data.out", "w", stdout);
    #endif
    
    while (scanf("%d %d", &n, &m)!=EOF && (n||m)) {
        rep(i, 1, n+1) {
            scanf("%d", &a[i]);
        }
        solve();
    }
    
    #ifndef ONLINE_JUDGE
        printf("time = %d.
", (int)clock());
    #endif
    
    return 0;
}

数据生成器。

from random import randint, shuffle
import shutil
import string


def GenDataIn():
    with open("data.in", "w") as fout:
        t = 22
        bound = 10**4
        for tt in xrange(t):
            n = randint(1800, 2000)
            k = randint(1, 25)
            fout.write("%d %d
" % (n, k))
            dataList = []
            for i in xrange(n):
                x = randint(-bound, bound)
                dataList.append(x)
            fout.write(" ".join(map(str, dataList)) + "
")
        fout.write("0 0
")        
        
                
def MovDataIn():
    desFileName = "F:eclipse_prjworkspacehdojdata.in"
    shutil.copyfile("data.in", desFileName)

    
if __name__ == "__main__":
    GenDataIn()
    MovDataIn()