《程序员代码面试指南》第八章 数组和矩阵问题 子矩阵的最大累加和问题

题目

子矩阵的最大累加和问题

java代码

package com.lizhouwei.chapter8;

/**
 * @Description: 子矩阵的最大累加和问题
 * @Author: lizhouwei
 * @CreateDate: 2018/5/8 21:33
 * @Modify by:
 * @ModifyDate:
 */
public class Chapter8_17 {

    public int maxSum(int[][] matrix) {
        int curSum = 0;
        int maxSum = Integer.MIN_VALUE;
        int[] help = new int[matrix[0].length];
        for (int i = 0; i < matrix.length; i++) {
            curSum=0;
            for (int j = 0; j < matrix[0].length; j++) {
                help[j] = help[j] + matrix[i][j];
                curSum = curSum + help[j];
                maxSum = Math.max(maxSum, curSum);
                curSum = curSum < 0 ? 0 : curSum;
            }
        }
        return maxSum;
    }

    //测试
    public static void main(String[] args) {
        Chapter8_17 chapter = new Chapter8_17();
        int[][] matrix = {{-90, 48, 78}, {64, -40, 64}, {-81, -7, 66}};
        System.out.print("矩阵 matrix = {{-90, 48, 78}, {64, -40, 64}, {-81, -7, 66}}最大累加和为:");
        int res = chapter.maxSum(matrix);
        System.out.print(res);
    }
}

结果