public class Solution {    public boolean searchMatrix(int[][] matrix, int target) {        int low=0, high=matrix.length-1;        while (low<high) {            int mid = (low+high)/2+1;            if (matrix[mid][0] > target) high = mid-1;            else low = mid;        }                int index1 = low;                low = 0;        high = matrix[0].length-1;        while (low<high) {            int mid = (low+high)/2+1;            if (matrix[index1][mid] > target) high = mid-1;            else low = mid;        }                return matrix[index1][low] == target;    }}