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package 02.mca_01;
// 牛客的测试链接:
// https://www.nowcoder.com/questionTerminal/8ecfe02124674e908b2aae65aad4efdf
// 请同学们务必参考如下代码中关于输入、输出的处理
// 这是输入输出处理效率很高的写法
// 把如下的全部代码拷贝进java编辑器
// 把文件大类名字改成Main可以直接通过
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.StreamTokenizer;
public class Code01_CherryPickup {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
StreamTokenizer in = new StreamTokenizer(br);
PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
while (in.nextToken() != StreamTokenizer.TT_EOF) {
int M = (int) in.nval;
in.nextToken();
int N = (int) in.nval;
int[][] matrix = new int[M][N];
for (int i = 0; i < M; i++) {
for (int j = 0; j < N; j++) {
in.nextToken();
matrix[i][j] = (int) in.nval;
}
}
out.println(cherryPickup(matrix));
out.flush();
}
}
public static int cherryPickup(int[][] grid) {
int N = grid.length;
int M = grid[0].length;
int[][][] dp = new int[N][M][N];
for (int i = 0; i < N; i++) {
for (int j = 0; j < M; j++) {
for (int k = 0; k < N; k++) {
dp[i][j][k] = Integer.MIN_VALUE;
}
}
}
int ans = process(grid, 0, 0, 0, dp);
return ans < 0 ? 0 : ans;
}
public static int process(int[][] grid, int x1, int y1, int x2, int[][][] dp) {
if (x1 == grid.length || y1 == grid[0].length || x2 == grid.length || x1 + y1 - x2 == grid[0].length) {
return Integer.MIN_VALUE;
}
if (dp[x1][y1][x2] != Integer.MIN_VALUE) {
return dp[x1][y1][x2];
}
if (x1 == grid.length - 1 && y1 == grid[0].length - 1) {
dp[x1][y1][x2] = grid[x1][y1];
return dp[x1][y1][x2];
}
int next = Integer.MIN_VALUE;
next = Math.max(next, process(grid, x1 + 1, y1, x2 + 1, dp));
next = Math.max(next, process(grid, x1 + 1, y1, x2, dp));
next = Math.max(next, process(grid, x1, y1 + 1, x2, dp));
next = Math.max(next, process(grid, x1, y1 + 1, x2 + 1, dp));
if (grid[x1][y1] == -1 || grid[x2][x1 + y1 - x2] == -1 || next == -1) {
dp[x1][y1][x2] = -1;
return dp[x1][y1][x2];
}
if (x1 == x2) {
dp[x1][y1][x2] = grid[x1][y1] + next;
return dp[x1][y1][x2];
}
dp[x1][y1][x2] = grid[x1][y1] + grid[x2][x1 + y1 - x2] + next;
return dp[x1][y1][x2];
}
}