class Solution {
public boolean searchMatrix(int[][] matrix, int target) {
for (int i = 0; i < matrix.length; i ++ ) {
if (target < matrix[i][0]) return false;
else {
int l = 0, r = matrix[i].length - 1;
while (l < r) {
int mid = l + r + 1 >> 1;
if (matrix[i][mid] <= target) l = mid;
else r = mid - 1;
}
if (matrix[i][l] == target) return true;
}
}
return false;
}
}