<p>编写一个高效的算法来判断 <code>m x n</code> 矩阵中,是否存在一个目标值。该矩阵具有如下特性:</p> <ul> <li>每行中的整数从左到右按升序排列。</li> <li>每行的第一个整数大于前一行的最后一个整数。</li> </ul> <p> </p> <p><strong>示例 1:</strong></p> <img alt="" src="https://assets.leetcode.com/uploads/2020/10/05/mat.jpg" style="width: 322px; height: 242px;" /> <pre> <strong>输入:</strong>matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 3 <strong>输出:</strong>true </pre> <p><strong>示例 2:</strong></p> <img alt="" src="https://assets.leetcode-cn.com/aliyun-lc-upload/uploads/2020/11/25/mat2.jpg" style="width: 322px; height: 242px;" /> <pre> <strong>输入:</strong>matrix = [[1,3,5,7],[10,11,16,20],[23,30,34,60]], target = 13 <strong>输出:</strong>false </pre> <p> </p> <p><strong>提示:</strong></p> <ul> <li><code>m == matrix.length</code></li> <li><code>n == matrix[i].length</code></li> <li><code>1 <= m, n <= 100</code></li> <li><code>-10<sup>4</sup> <= matrix[i][j], target <= 10<sup>4</sup></code></li> </ul>