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Description
tab: English
<p>There is a robot on an <code>m x n</code> grid. The robot is initially located at the <strong>top-left corner</strong> (i.e., <code>grid[0][0]</code>). The robot tries to move to the <strong>bottom-right corner</strong> (i.e., <code>grid[m - 1][n - 1]</code>). The robot can only move either down or right at any point in time.</p>
<p>Given the two integers <code>m</code> and <code>n</code>, return <em>the number of possible unique paths that the robot can take to reach the bottom-right corner</em>.</p>
<p>The test cases are generated so that the answer will be less than or equal to <code>2 * 10<sup>9</sup></code>.</p>
<p> </p>
<p><strong class="example">Example 1:</strong></p>
<img src="https://assets.leetcode.com/uploads/2018/10/22/robot_maze.png" style="width: 400px; height: 183px;" />
<pre>
<strong>Input:</strong> m = 3, n = 7
<strong>Output:</strong> 28
</pre>
<p><strong class="example">Example 2:</strong></p>
<pre>
<strong>Input:</strong> m = 3, n = 2
<strong>Output:</strong> 3
<strong>Explanation:</strong> From the top-left corner, there are a total of 3 ways to reach the bottom-right corner:
1. Right -> Down -> Down
2. Down -> Down -> Right
3. Down -> Right -> Down
</pre>
<p> </p>
<p><strong>Constraints:</strong></p>
<ul>
<li><code>1 <= m, n <= 100</code></li>
</ul>
---
[submissions](https://leetcode.com/problems/unique-paths/submissions/) | [solutions](https://leetcode.com/problems/unique-paths/solutions/)
tab: 中文
<p>一个机器人位于一个 <code>m x n</code><em> </em>网格的左上角 （起始点在下图中标记为 “Start” ）。</p>
<p>机器人每次只能向下或者向右移动一步。机器人试图达到网格的右下角（在下图中标记为 “Finish” ）。</p>
<p>问总共有多少条不同的路径？</p>
<p> </p>
<p><strong>示例 1：</strong></p>
<img src="https://pic.leetcode.cn/1697422740-adxmsI-image.png" style="width: 400px; height: 183px;" />
<pre>
<strong>输入：</strong>m = 3, n = 7
<strong>输出：</strong>28</pre>
<p><strong>示例 2：</strong></p>
<pre>
<strong>输入：</strong>m = 3, n = 2
<strong>输出：</strong>3
<strong>解释：</strong>
从左上角开始，总共有 3 条路径可以到达右下角。
1. 向右 -> 向下 -> 向下
2. 向下 -> 向下 -> 向右
3. 向下 -> 向右 -> 向下
</pre>
<p><strong>示例 3：</strong></p>
<pre>
<strong>输入：</strong>m = 7, n = 3
<strong>输出：</strong>28
</pre>
<p><strong>示例 4：</strong></p>
<pre>
<strong>输入：</strong>m = 3, n = 3
<strong>输出：</strong>6</pre>
<p> </p>
<p><strong>提示：</strong></p>
<ul>
<li><code>1 <= m, n <= 100</code></li>
<li>题目数据保证答案小于等于 <code>2 * 10<sup>9</sup></code></li>
</ul>
---
[提交记录](https://leetcode.cn/problems/unique-paths/submissions/) | [题解](https://leetcode.cn/problems/unique-paths/solution/)
Solutions & Notes
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