240.Search a 2D Matrix II

1- Binary Search line by line O(nlogn)

class Solution {
    public boolean binarySearch(int[] a, int target){
        int n = a.length;
        int left = 0;
        int right = n - 1; 
        while(left <= right){
            int mid = left + (right - left) / 2;
            if(a[mid] == target){
                return true; 
            }
            else if(a[mid] > target){
                right = mid - 1;
            }
            else{
                left = mid + 1;
            }
        }
        return false;
    }
    public boolean searchMatrix(int[][] matrix, int target) {
        boolean ans;
        for(int i = 0; i < matrix.length; i++){
            ans = binarySearch(matrix[i], target);
            if(ans){
                return true;
            }
        }
        return false;
    }
}

2-Two Pointer O(m + n)

https://leetcode.com/problems/search-a-2d-matrix-ii/solution/

class Solution {
    public boolean searchMatrix(int[][] matrix, int target) {
        int x = matrix.length - 1;
        int y = 0;
        while(x >= 0 && y < matrix[0].length){
            if(matrix[x][y] > target){
                x--;
            }
            else if(matrix[x][y] < target){
                y++;
            }
            else{
                return true;
            }
        }
        return false;
    }
}