62 unique path II

Author: Lei Cao

README.md

@@ -174,7 +174,7 @@ LeetCode
 |65|[Add Binary](https://oj.leetcode.com/problems/add-binary/)| [C++](./algorithms/addBinary/addBinary.cpp)|Easy|
 |64|[Merge Two Sorted Lists](https://oj.leetcode.com/problems/merge-two-sorted-lists/)| [C++](./algorithms/mergeTwoSortedList/mergeTwoSortedList.cpp)|Easy|
 |63|[Minimum Path Sum](https://oj.leetcode.com/problems/minimum-path-sum/)| [C++](./algorithms/minimumPathSum/minimumPathSum.cpp)|Medium|
-|62|[Unique Paths II](https://oj.leetcode.com/problems/unique-paths-ii/)| [C++](./algorithms/uniquePaths/uniquePaths.II.cpp)|Medium|
+|62|[Unique Paths II](https://oj.leetcode.com/problems/unique-paths-ii/)| [C++](./algorithms/uniquePaths/uniquePaths.II.cpp), [Java](./algorithms-java/src/dynamicProgramming/uniquePaths/uniquePathsII.java)|Medium|
 |61|[Unique Paths](https://oj.leetcode.com/problems/unique-paths/)| [C++](./algorithms/uniquePaths/uniquePaths.cpp), [Java](./algorithms-java/src/dynamicProgramming/uniquePaths/uniquePaths.java)|Medium|
 |60|[Rotate List](https://oj.leetcode.com/problems/rotate-list/)| [C++](./algorithms/rotateList/rotateList.cpp)|Medium|
 |59|[Permutation Sequence](https://oj.leetcode.com/problems/permutation-sequence/)| [C++](./algorithms/permutationSequence/permutationSequence.cpp)|Medium|
@@ -254,4 +254,4 @@ LeetCode
 | # | Title | Solution | Difficulty |
 |---| ----- | -------- | ---------- |
 |1|[Search in a big sorted array](http://www.lintcode.com/en/problem/search-in-a-big-sorted-array/)|[Java](./algorithms-java/src/searchInABigSortedArray/searchInABigSortedArray.java)|Medium|
-[2][Search Range in Binary Search Tree](http://www.lintcode.com/en/problem/search-range-in-binary-search-tree/) | [Java](./algorithms-java/src/searchRangeInBinarySearchTree/searchRangeInBinarySearchTree.java)|Medium|
+|2|[Search Range in Binary Search Tree](http://www.lintcode.com/en/problem/search-range-in-binary-search-tree/) | [Java](./algorithms-java/src/searchRangeInBinarySearchTree/searchRangeInBinarySearchTree.java)|Medium|

algorithms-java/src/dynamicProgramming/uniquePaths/uniquePathsII.java

@@ -0,0 +1,73 @@
+// Source : https://oj.leetcode.com/problems/unique-paths-ii/
+// Inspired by : http://www.jiuzhang.com/solutions/unique-paths/
+// Author : Lei Cao
+// Date   : 2015-10-11
+
+/**********************************************************************************
+ *
+ * Follow up for "Unique Paths":
+ *
+ * Now consider if some obstacles are added to the grids. How many unique paths would there be?
+ *
+ * An obstacle and empty space is marked as 1 and 0 respectively in the grid.
+ *
+ * For example,
+ * There is one obstacle in the middle of a 3x3 grid as illustrated below.
+ *
+ * [
+ *   [0,0,0],
+ *   [0,1,0],
+ *   [0,0,0]
+ * ]
+ *
+ * The total number of unique paths is 2.
+ *
+ * Note: m and n will be at most 100.
+ *
+ **********************************************************************************/
+
+package dynamicProgramming.uniquePaths;
+
+public class uniquePathsII {
+    /**
+     * @param obstacleGrid: A list of lists of integers
+     * @return: An integer
+     */
+    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
+        if (obstacleGrid.length == 0 || obstacleGrid[0].length ==0) {
+            return 0;
+        }
+        if (obstacleGrid[0][0] == 1) {
+            return 0;
+        }
+        int m = obstacleGrid.length;
+        int n = obstacleGrid[0].length;
+        // write your code here
+        int[][] matrix = new int[m][n];
+        for (int i = 0; i < m; i++) {
+            if (obstacleGrid[i][0] != 1) {
+                matrix[i][0] = 1;
+            } else {
+                break;
+            }
+        }
+        for (int i = 0; i < n; i++) {
+            if (obstacleGrid[0][i] != 1) {
+                matrix[0][i] = 1;
+            } else {
+                break;
+            }
+        }
+
+        for (int i = 1; i < m; i++) {
+            for (int j = 1; j < n; j++) {
+                if (obstacleGrid[i][j] == 1) {
+                    matrix[i][j] = 0;
+                } else {
+                    matrix[i][j] = matrix[i-1][j] + matrix[i][j-1];
+                }
+            }
+        }
+        return matrix[m-1][n-1];
+    }
+}

algorithms-java/src/dynamicProgramming/uniquePaths/uniquePathsIITest.java

@@ -0,0 +1,29 @@
+package dynamicProgramming.uniquePaths;
+
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+/**
+ * Created by leicao on 11/10/15.
+ */
+public class uniquePathsIITest {
+
+    @Test
+    public void testUniquePathsWithObstacles() throws Exception {
+        int[][][] inputs = {
+            {
+                {0,0,0},
+                {0,1,0},
+                {0,0,0},
+            }
+        };
+        int[] results = {2};
+        for (int i = 0; i < inputs.length; i++) {
+            uniquePathsII u = new uniquePathsII();
+            int r = u.uniquePathsWithObstacles(inputs[i]);
+            System.out.println(r);
+            assertEquals(results[i], r);
+        }
+    }
+}