Envío 1179

Código

import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Arrays;

class Main{
	static class Reader {
		final private int BUFFER_SIZE = 1 << 16;
		private DataInputStream din;
		private byte[] buffer;
		private int bufferPointer, bytesRead;

		public Reader() {
			din = new DataInputStream(System.in);
			buffer = new byte[BUFFER_SIZE];
			bufferPointer = bytesRead = 0;
		}

		public Reader(String file_name) throws IOException {
			din = new DataInputStream(new FileInputStream(file_name));
			buffer = new byte[BUFFER_SIZE];
			bufferPointer = bytesRead = 0;
		}

		public String readLine() throws IOException {
			byte[] buf = new byte[64]; // line length
			int cnt = 0, c;
			while ((c = read()) != -1) {
				if (c == '\n')
					break;
				buf[cnt++] = (byte) c;
			}
			return new String(buf, 0, cnt);
		}

		public int nextInt() throws IOException {
			int ret = 0;
			byte c = read();
			while (c <= ' ')
				c = read();
			boolean neg = (c == '-');
			if (neg)
				c = read();
			do {
				ret = ret * 10 + c - '0';
			} while ((c = read()) >= '0' && c <= '9');

			if (neg)
				return -ret;
			return ret;
		}

		public long nextLong() throws IOException {
			long ret = 0;
			byte c = read();
			while (c <= ' ')
				c = read();
			boolean neg = (c == '-');
			if (neg)
				c = read();
			do {
				ret = ret * 10 + c - '0';
			} while ((c = read()) >= '0' && c <= '9');
			if (neg)
				return -ret;
			return ret;
		}

		public double nextDouble() throws IOException {
			double ret = 0, div = 1;
			byte c = read();
			while (c <= ' ')
				c = read();
			boolean neg = (c == '-');
			if (neg)
				c = read();

			do {
				ret = ret * 10 + c - '0';
			} while ((c = read()) >= '0' && c <= '9');

			if (c == '.') {
				while ((c = read()) >= '0' && c <= '9') {
					ret += (c - '0') / (div *= 10);
				}
			}

			if (neg)
				return -ret;
			return ret;
		}

		private void fillBuffer() throws IOException {
			bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
			if (bytesRead == -1)
				buffer[0] = -1;
		}

		private byte read() throws IOException {
			if (bufferPointer == bytesRead)
				fillBuffer();
			return buffer[bufferPointer++];
		}

		public void close() throws IOException {
			if (din == null)
				return;
			din.close();
		}
	}

	private static int maxSubArray(int[] compressed) {
		int maxValue = Integer.MIN_VALUE;
		for (int i = 0; i < compressed.length; i++) {
			int sum = 0;
			for (int j = i; j < compressed.length; j++) {
				sum += compressed[j];
				maxValue = Math.max(sum, maxValue);
			}
		}
		return maxValue;
	}

	public static void main(String[] args) throws IOException {
		Reader s = new Reader();
		int rows, cols;
		rows = s.nextInt();
		cols = s.nextInt();
		int matrix[][] = new int[rows][cols];
		// fill matrix
		for (int row = 0; row < rows; row++) {
			for (int col = 0; col < cols; col++) {
				matrix[row][col] = s.nextInt();
			}
		}
		int compressed[] = new int[cols];
		int ans = Integer.MIN_VALUE;
		for (int r = 0; r < rows; r++) {
			Arrays.fill(compressed, 0);
			for (int r1 = r; r1 < rows; r1++) {
				for (int c = 0; c < cols; c++) {
					compressed[c] += matrix[r1][c];
				}
				ans = Math.max(ans, maxSubArray(compressed));
			}
		}
		System.out.println(ans);
	}
}