Given a non-empty 2D matrix matrix and an integer k, find the max sum of a rectangle in the matrix such that its sum is no larger than k.
Example:
Given matrix = [ [1, 0, 1], [0, -2, 3]]k = 2
The answer is 2
. Because the sum of rectangle [[0, 1], [-2, 3]]
is 2 and 2 is the max number no larger than k (k = 2).
Note:
- The rectangle inside the matrix must have an area > 0.
- What if the number of rows is much larger than the number of columns?
Credits:
Special thanks to for adding this problem and creating all test cases.Analysis:
Take the following analysis from https://discuss.leetcode.com/topic/48854/java-binary-search-solution-time-complexity-min-m-n-2-max-m-n-log-max-m-n
/* first consider the situation matrix is 1D we can save every sum of 0~i(0<=i
1 public class Solution { 2 public int maxSumSubmatrix(int[][] matrix, int k) { 3 if (matrix.length == 0 || matrix[0].length == 0) 4 return Integer.MIN_VALUE; 5 6 int res = Integer.MIN_VALUE; 7 int row = matrix.length; 8 int col = matrix[0].length; 9 int m = Math.min(row, col);10 int n = Math.max(row, col);11 boolean moreCol = (col > row);12 13 for (int i = 0; i < m; i++) {14 int[] sum = new int[n];15 for (int j = i; j >= 0; j--) {16 int val = 0;17 TreeSetsumSet = new TreeSet ();18 sumSet.add(0);19 for (int l = 0; l < n; l++) {20 sum[l] = sum[l] + ((moreCol) ? matrix[j][l] : matrix[l][j]);21 val += sum[l];22 Integer other = sumSet.ceiling(val - k);23 if (other != null) {24 res = Math.max(res, val - other);25 }26 sumSet.add(val);27 }28 }29 }30 31 return res;32 }33 }