hdu2845dp问题

看了一眼题目，简单dp问题，但超时了一晚上，试了各种方法无法解决，最终放弃java，改用C直接过，我哭了。。。。

#include<stdio.h>
#include<string.h>

#define maxn 200010
int dp[maxn],ans[maxn],map[maxn];
int max(int x,int y)
{
    return x>y?x:y;
}
int main()
{
    int i,j;
    int n,m;
    int xx;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        int cc,dd;
        int aa,bb;
        int res;
        for(i=0;i<n;i++)
        {
            for(j=0;j<m;j++)
            {
                scanf("%d",&xx);
                if (j==0) {
                    aa = xx;
                    bb = xx;
                }else if (j==1) {
                    bb = max(aa, xx);
                }else {
                    int tmp = bb;
                    bb = max(bb, aa+xx);
                    aa = tmp;
                }
            }
            if (i==0) {
                cc = bb;
                dd = bb;
            }else if (i==1) {
                dd = max(dd, bb);
            }else {
                int tmp1 = dd;
                dd = max(dd, cc+bb);
                cc = tmp1;
            }
            res = dd;
        }
        printf("%d\n",res);
    }
}

下面是永远超时的java代码：

import java.util.Scanner;

public class hdu2845_2 {

    public static void main(String[] args) {
        // TODO 自动生成的方法存根
        Scanner sc = new Scanner(System.in);
        while (true) {
            int n = sc.nextInt();
            int m = sc.nextInt();
            int res = 0;
            int cc = 0;
            int dd = 0;
            for (int i = 0; i < n; i++) {
                int aa = 0;
                int bb = 0;                
                for (int j = 0; j < m; j++) {
                    int xx = sc.nextInt();
                    if (j==0) {
                        aa = xx;
                        bb = xx;
                    }else if (j==1) {
                        bb = Math.max(aa, xx);
                    }else {
                        int tmp = bb;
                        bb = Math.max(bb, aa+xx);
                        aa = tmp;
                    }
                }

                if (i==0) {
                    cc = bb;
                    dd = bb;
                }else if (i==1) {
                    dd = Math.max(dd, bb);
                }else {
                    int tmp1 = dd;
                    dd = Math.max(dd, cc+bb);
                    cc = tmp1;
                }
                res = dd;
            }
            System.out.println(res);
        }

    }

}