240. Search a 2D Matrix II.java

class Solution {
    public boolean searchMatrix(int[][] matrix, int target) {
        //从一个能增能减的点根据与target的大小关系移动
        if(matrix == null || matrix.length == 0 || matrix[0].length == 0)
            return false;
        int row = 0;
        int col = matrix[0].length - 1;
        while(row < matrix.length && col >= 0) {
            if(matrix[row][col] > target) {
                col--;
            }
            else if(matrix[row][col] < target) {
                row++;
            }
            else {
                return true;
            }
        }
        return false;
    }
}