UVALive 5983 二分答案+dp

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;
#define inf (0x3f3f3f3f)
typedef long long int LL;

#include <iostream>
#include <sstream>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <string>
const int maxn=500+20;
LL dp[maxn][maxn];
int n,m;
int a[maxn][maxn];
bool check (LL val)
{
dp[1][1]=val;
for (int i=1;i<=n;++i)
{
for (int j=1;j<=m;++j)
{
if (i==1 && j==1)continue;
if (dp[i-1][j]<=0) dp[i-1][j]=-inf; //如果小于0，证明已经不能走了
if (dp[i][j-1]<=0) dp[i][j-1]=-inf;
if (dp[i-1][j]<=0 && dp[i][j-1]<=0) dp[i][j]=-inf;
else dp[i][j]=max(dp[i-1][j],dp[i][j-1])+a[i][j];
}
}
return dp
[m]>0;
}
void work ()
{
scanf("%d%d",&n,&m);
for (int i=1;i<=n;++i)
for (int j=1;j<=m;++j)
scanf("%d",&a[i][j]);
LL begin=1,end=1LL*500*500*1000+20;
while (begin<=end)
{
LL mid = (begin+end)>>1;
//printf ("%d\n",mid);
if (check(mid))
end=mid-1;
else begin=mid+1;
}
printf ("%lld\n",begin);
//check(998);
//check(3);
//printf ("%d\n",check(1002));
//    printf ("%lld\n",dp[2][4]);
return ;
}

int main()
{
#ifdef local
freopen("data.txt","r",stdin);
#endif
for (int i=1;i<=500;++i)
{
dp[0][i]=-inf;
dp[i][0]=-inf;
}
dp[0][0]=-inf;
dp[0][1]=0;
dp[1][0]=0;
int t;
scanf("%d",&t);
while (t--) work();
return 0;
}