0240 Search a 2D Matrix II

Question

My Solution 1: Intuition

class Solution {
    public boolean searchMatrix(int[][] matrix, int target) {
        int m = matrix.length;
        int n = matrix[0].length;

        if(target > matrix[m-1][n-1]
        || target < matrix[0][0]){
            return false;
        }

        for(int[]r: matrix){
            if(r[0] <= target && r[n-1] >= target){
                if(searchArray(r, target)){
                    return true;
                }
            }
        }   
        
        return false;
    }


    private boolean searchArray(int[] row, int target){
        int end = row.length-1;
        int begin = 0;
        while(begin <= end){
            int mid = begin + (end - begin) / 2;
            if(row[mid] == target){
                return true;
            }else if(row[mid] > target){
                end = mid-1;
            }else if(row[mid] < target){
                begin = mid+1;
            }
        }

        return false;
    }
}

My Solution 2:

class Solution {
    public boolean searchMatrix(int[][] matrix, int target) {
        int m = matrix.length;
        int n = matrix[0].length;
        if(target < matrix[0][0]
        || target > matrix[m-1][n-1]){
            return false;
        }

        // start from top-right point
        int col = n - 1;
        int row = 0;

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

        return false;
    }
}