Submission #9687

#	Time	Username	Problem	Language	Result	Execution time	Memory
9687		corea	On grid (kriii2_O)	C++14	0 / 4	60 ms	225880 KiB

O

#include <cstdio>
#include <iostream>
#include <cstring>
#include <tuple>
#include <cassert>
#include <vector>
#include <algorithm>

using namespace std;
 
#define REP(i, n) for(int i=0; i < n; ++i)

int n, m;
int a[305][305];

long long S[305][305];
long long V[305][305];
long long C[305][305];
long long M[305][305][305];

long long sum(int i1, int j1, int i2, int j2) // inclusive
{
	return S[i2][j2] - S[i2][j1 - 1] - S[i1 - 1][j2] + S[i1 - 1][j1 - 1];
}

long long compute_M(int i, int j, int k) {
	if(j == 1) {
		int l = 0;
		return C[k][l] - S[i][l] - S[k][j] + S[k][l];
	}
	else {
		int left = M[i][j - 1][k] - S[k][j] + S[k][j - 1];
		int l = j - 1;
		int right = C[k][l] - S[i][l] - S[k][j] + S[k][l];

#if 0
		if(i == 2 && j == 3 && k == 1)  {
			printf("L = %d\n", left);
			printf("R = %d\n", right);
		}
#endif

		return max(left, right);
	}
}

long long go() {

	memset(C, 0, sizeof(C));
	memset(M, 0, sizeof(M));
	memset(V, 0, sizeof(V));

	for(int i = 1; i <= n; ++ i) {
		for(int j = 1; j <= m; ++ j) {
			S[i][j] = a[i][j] + S[i-1][j] + S[i][j-1] - S[i-1][j-1];
		}
	}

	const long long INF = 1LL << 50;
	for(int i = 1; i <= n; ++ i) {
		V[i][0] = -INF;
		C[i][0] = -INF;
	}
	for(int j = 1; j <= m; ++ j) {
		V[0][j] = -INF;
		C[0][j] = -INF;
	}
	
	for(int i = 1; i <= n; ++ i) {
		for(int j = 1; j <= m; ++ j) {

			// M[i][j] = max { C[k][l] - S[i][l] - S[k][j] + S[k][] }
			//           k < i, l < j
			// M[i][j-1] = max { C[k][l] - S[i][l] - S[k][j] + S[k][l] }
			//           k < i, l < j-1

			long long maxi = 0;
			for(int k = 0; k < i; ++ k) {
				M[i][j][k] = compute_M(i, j, k);
//				printf("M %d %d %d = %lld\n", i, j, k, M[i][j][k]);
				maxi = max(maxi, M[i][j][k]);
			}

			C[i][j] = maxi + S[i][j];

#if 0
			V[i][j] = -987987;
			for(int k = 0; k < i; ++ k) {
				for(int l = 0; l < j; ++ l) {
					V[i][j] = max(V[i][j], V[k][l] - S[i][l] - S[k][j] + S[k][l] + S[i][j]);
				}
			}
#endif

//			printf("[%3lld]<%3lld> / %2lld+%2lld  ", C[i][j], V[i][j], S[i][j], maxi);
		}
//		printf("\n");
	}
	return C[n][m];
}

int main() {
	while(cin >> n >> m && n && m ) {
		for(int i = 1; i <= n; ++ i) {
			for(int j=1; j<=m; ++j) {
				cin >> a[i][j];
			}
		}
		cout << go() << endl;
	}

	return 0;
}

• Subtask 1: 0 / 1
• Subtask 2: 0 / 3