package leetcode_1To300;

/**
 * 本代码来自 Cspiration，由 @Cspiration 提供
 * 题目来源：http://leetcode.com
 * - Cspiration 致力于在 CS 领域内帮助中国人找到工作，让更多海外国人受益
 * - 现有课程：Leetcode Java 版本视频讲解（1-900题）（上）（中）（下）三部
 * - 算法基础知识（上）（下）两部；题型技巧讲解（上）（下）两部
 * - 节省刷题时间，效率提高2-3倍，初学者轻松一天10题，入门者轻松一天20题
 * - 讲师：Edward Shi
 * - 官方网站：https://cspiration.com
 * - 版权所有，转发请注明出处
 */
public class _240_Searcha2DMatrixII {
    /**
     * 240. Search a 2D Matrix II
     * Write an efficient algorithm that searches for a value in an m x n matrix.
     * This matrix has the following properties:

     Integers in each row are sorted in ascending from left to right.
     Integers in each column are sorted in ascending from top to bottom.
     For example,

     Consider the following matrix:

     [
     [1,   4,  7, 11, 15],
     [2,   5,  8, 12, 19],
     [3,   6,  9, 16, 22],
     [10, 13, 14, 17, 24],
     [18, 21, 23, 26, 30]
     ]
     Given target = 5, return true.

     Given target = 20, return false.

     time : O(m + n)
     space : O(1)

     * @param matrix
     * @param target
     * @return
     */
    public boolean searchMatrix(int[][] matrix, int target) {
        if (matrix == null || matrix.length == 0) return false;
        int row = 0;
        int col = matrix[0].length - 1;

        while (col >= 0 && row <= matrix.length - 1) {
            if (target == matrix[row][col]) {
                return true;
            } else if (target < matrix[row][col]) {
                col--;
            } else {
                row++;
            }
        }
        return false;
    }
}