Matrix Swapping II hdu2830

Matrix Swapping II

Time Limit: 9000/3000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 1931    Accepted Submission(s): 1297

Problem Description

Given an N * M matrix with each entry equal to 0 or 1. We can find some rectangles in the matrix whose entries are all 1, and we define the maximum area of such rectangle as this matrix’s goodness.
We can swap any two columns any times, and we are to make the goodness of the matrix as large as possible.

 

Input

There are several test cases in the input. The first line of each test case contains two integers N and M (1 ≤ N,M ≤ 1000). Then N lines follow, each contains M numbers (0 or 1), indicating the N * M matrix

 

Output

Output one line for each test case, indicating the maximum possible goodness.

 

Sample Input

3 41011100100013 4101010010001

 

Sample Output

42Note: Huge Input, scanf() is recommended.
尽然忘了加代码。。。真是蠢的不行。。
import java.util.Arrays;import java.util.Scanner;public class hdu2830 {public static void main(String[] args) {Scanner scanner = new Scanner(System.in);while (scanner.hasNextLine()) {String[] s = scanner.nextLine().trim().split(" ", 2);if (s[0] == null || s[0].equals(""))break;int n = Integer.valueOf(s[0]);int m = Integer.valueOf(s[1]);int[][] high = new int[n + 2][m + 2];// 预处理每行的高度for (int i = 0; i < n; i++) {String line = scanner.nextLine().trim();for (int j = 0; j < line.length(); j++) {if (line.charAt(j) == '1')high[i + 1][j + 1] = high[i][j + 1] + 1;}}// 处理每一行int area = 0;for (int i = 1; i <= n; i++) {int[] h = new int[m + 2];h[0] = -1;h[m + 1] = Integer.MAX_VALUE;//为了排序不乱，把数组最后一个数设为最大值,排完序再修改回来for (int j = 1; j <= m; j++)h[j] = high[i][j];Arrays.sort(h);h[m + 1] = -1;//for (int j = 0; j <= m+1; j++)//System.out.print(h[j]+" ");//System.out.println();int[] left = new int[m + 2];int[] right = new int[m + 2];left[0] = 1;right[m + 1] = -1;for (int j = 1; j <= m; j++) {left[j] = j;while (h[left[j] - 1] >= h[j])left[j] = left[left[j] - 1];}for (int j = m; j >= 1; j--) {right[j] = j;while (h[right[j] + 1] >= h[j])right[j] = right[right[j] + 1];}//for (int j = 0; j <= m+1; j++)//System.out.print(left[j]+" ");//System.out.println();////for (int j = 0; j <= m+1; j++)//System.out.print(right[j]+" ");//System.out.println();for (int j = 1; j <= m; j++) {if (area < (right[j] - left[j] + 1) * h[j])area = (right[j] - left[j] + 1) * h[j];}}System.out.println(area);}scanner.close();}}