[HDU#1024]Max Sum Plus Plus

Max Sum Plus Plus

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 24152    Accepted Submission(s): 8265

Problem Description

Now I think you have got an AC in Ignatius.L's "Max Sum" problem. To be a brave ACMer, we always challenge ourselves to more difficult problems. Now you are faced with a more difficult problem.

Given a consecutive number sequence S1, S2, S3, S4 … Sx, … Sn (1 ≤ x ≤ n ≤ 1,000,000, -32768 ≤ Sx ≤ 32767). We define a function sum(i, j) = Si + … + Sj (1 ≤ i ≤ j ≤ n).

Now given an integer m (m > 0), your task is to find m pairs of i and j which make sum(i1, j1) + sum(i2, j2) + sum(i3, j3) + … + sum(im, jm) maximal (ix ≤ iy ≤ jx or ix ≤ jy ≤ jx is not allowed).

But I`m lazy, I don't want to write a special-judge module, so you don't have to output m pairs of i and j, just output the maximal summation of sum(ix, jx)(1 ≤ x ≤ m) instead. ^_^

 

Input

Each test case will begin with two integers m and n, followed by n integers S1, S2, S3 … Sn.
Process to the end of file.

 

Output

Output the maximal summation described above in one line.

 

Sample Input

1 3 1 2 3
2 6 -1 4 -2 3 -2 3

 

Sample Output

6
8

经典的动态规划+滚动数组题

#include<iostream>
#define max(a,b) (a>b?a:b)
#define MAX 1000000
#define INF 0x7fffffff
using namespace std;
int main(void)
{
#ifndef ONLINE_JUDGE 
 freopen("in.txt", "r", stdin);
#endif
 int n, m;
 while (cin >> n >> m)
 {
  int d[MAX+1];
  int dp[MAX + 1] = { 0 }; //前J个数,组成I组最大
  int mm[MAX+1] = { 0 };
  int mmax;
  for (int i = 1; i<=m; i++)
  {
   cin >> d[i];
  }
  for (int i = 0; i < n; i++)
  {
   mmax = -INF;
   for (int j = i+1; j <= m; j++)
   {
    dp[j] = max(dp[j - 1], mm[j - 1]) + d[j];
    mm[j - 1] = mmax;
    mmax = max(dp[j], mmax);
   }
  }
  cout << mmax << endl;
 }
 return 0;
}

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