solve problem Unique Paths II

Author: P-ppc

README.md

@@ -279,6 +279,7 @@ All solutions will be accepted!
 |430|[Flatten A Multilevel Doubly Linked List](https://leetcode-cn.com/problems/flatten-a-multilevel-doubly-linked-list/description/)|[java/py](./algorithms/FlattenAMultilevelDoublyLinkedList)|Medium|
 |138|[Copy List With Random Pointer](https://leetcode-cn.com/problems/copy-list-with-random-pointer/description/)|[java/py/js](./algorithms/CopyListWithRandomPointer)|Medium|
 |62|[Unique Paths](https://leetcode-cn.com/problems/unique-paths/description/)|[java/py/js](./algorithms/UniquePaths)|Medium|
+|63|[Unique Paths II](https://leetcode-cn.com/problems/unique-paths-ii/description/)|[java/py/js](./algorithms/UniquePathsII)|Medium|
 |162|[Find Peak Element](https://leetcode-cn.com/problems/find-peak-element/description/)|[java/py/js](./algorithms/FindPeakElement)|Medium|
 |200|[Number Of Islands](https://leetcode-cn.com/problems/number-of-islands/description/)|[java/py/js](./algorithms/NumberOfIslands)|Medium|
 |223|[Rectangle Area](https://leetcode-cn.com/problems/rectangle-area/description/)|[java/py/js](./algorithms/RectangleArea)|Medium|

algorithms/UniquePathsII/README.md

@@ -0,0 +1,2 @@
+# Unique Paths II
+This problem is easy to solve by dynamic programming, like [Unique Paths](./UniquePaths)

algorithms/UniquePathsII/Solution.java

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+class Solution {
+    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
+        int m = obstacleGrid.length;
+        int n = m > 0 ? obstacleGrid[0].length : 0;
+        
+        if (m == 0 || n == 0)
+            return 0;
+        
+        int[][] dp = new int[m][n];
+        dp[0][0] = obstacleGrid[0][0] == 0 ? 1 : 0;
+        
+        for (int i = 0; i < m; i++) {
+            for (int j = 0; j < n; j++) {
+                if (obstacleGrid[i][j] == 0)
+                    dp[i][j] += (i > 0 ? dp[i - 1][j] : 0) + (j > 0 ? dp[i][j - 1] : 0);
+            }
+        }
+        
+        return dp[m - 1][n - 1];
+    }
+}

algorithms/UniquePathsII/solution.js

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+/**
+ * @param {number[][]} obstacleGrid
+ * @return {number}
+ */
+var uniquePathsWithObstacles = function(obstacleGrid) {
+    let m = obstacleGrid.length,
+        n = m > 0 ? obstacleGrid[0].length : 0
+    
+    if (m == 0 || n == 0)
+        return 0
+    
+    dp = []
+    for (let i = 0; i < m; i++) {
+        let row = new Array(n)
+        row.fill(0)
+        dp.push(row)
+    }
+    
+    dp[0][0] = obstacleGrid[0][0] == 0 ? 1 : 0
+    
+    for (let i = 0; i < m; i++) {
+        for (let j = 0; j < n; j++) {
+            if (obstacleGrid[i][j] == 0)
+                dp[i][j] += (i > 0 ? dp[i - 1][j] : 0) + (j > 0 ? dp[i][j - 1] : 0)
+        }
+    }
+    
+    return dp[m - 1][n - 1]
+};

algorithms/UniquePathsII/solution.py

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+class Solution(object):
+    def uniquePathsWithObstacles(self, obstacleGrid):
+        """
+        :type obstacleGrid: List[List[int]]
+        :rtype: int
+        """
+        m = len(obstacleGrid)
+        n = len(obstacleGrid[0]) if m > 0 else 0
+        if m == 0 or n == 0:
+            return 0
+        
+        dp = []
+        for i in xrange(m):
+            row = [0] * n
+            dp.append(row)
+        
+        dp[0][0] = 1 if obstacleGrid[0][0] == 0 else 0
+        
+        for i in xrange(m):
+            for j in xrange(n):
+                if obstacleGrid[i][j] == 0:
+                    dp[i][j] += (dp[i - 1][j] if i > 0 else 0) + (dp[i][j - 1] if j > 0 else 0)
+        
+        return dp[m - 1][n - 1]