Timus 1146. Maximum Sum

/* ***********************************************
Author        :guanjun
Created Time  :2016/10/7 13:50:13
File Name     :timus1146.cpp
************************************************ */
#include <bits/stdc++.h>
#define ull unsigned long long
#define ll long long
#define mod 90001
#define INF 0x3f3f3f3f
#define maxn 10010
#define cle(a) memset(a,0,sizeof(a))
const ull inf = 1LL << 61;
const double eps=1e-5;
using namespace std;
priority_queue<int,vector<int>,greater<int> >pq;
struct Node{
    int x,y;
};
struct cmp{
    bool operator()(Node a,Node b){
        if(a.x==b.x) return a.y> b.y;
        return a.x>b.x;
    }
};

bool cmp(int a,int b){
    return a>b;
}
int a[110][110],n;
int sum[110][110];
int dp[110];
int main()
{
    #ifndef ONLINE_JUDGE
    //freopen("in.txt","r",stdin);
    #endif
    //freopen("out.txt","w",stdout);
    while(scanf("%d",&n)!=EOF){
        cle(sum);
        for(int i=1;i<=n;i++){
            for(int j=1;j<=n;j++){
                scanf("%d",&a[i][j]);
                sum[i][j]=sum[i][j-1]+a[i][j];
            }
        }
        int Max=-INF;
        //dp  求最大连续子序列 dp[i]代表以i为结尾的最大连续子序列的长度
        for(int i=1;i<=n;i++){
            for(int j=1;j<=i;j++){
                cle(dp);
                for(int k=1;k<=n;k++){
                    int tmp=sum[k][i]-sum[k][j-1];
                    if(dp[k-1]<0){
                        dp[k]=tmp;
                    }
                    else dp[k]=tmp+dp[k-1];
                    Max=max(dp[k],Max);
                }
            }
        }
        cout<<Max<<endl;
    }
    return 0;
}