#63 不同路径统计，带障碍物版本

Author: Isaaclot

main/src/dynamic_programming/LC_63_UniquePathsWithObstacles.java

@@ -118,4 +118,33 @@ public int uniquePathsWithObstaclesDP_Review(int[][] obstacleGrid) {
 
         return dp[rows - 1][column - 1];
     }
+
+    public int uniquePathsWithObstaclesDP_3rd(int[][] obstacleGrid) {
+        int rows = obstacleGrid.length;
+        int column = obstacleGrid[0].length;
+        int[][] dp = new int[rows][column];
+        if (obstacleGrid[0][0] == 1 || obstacleGrid[rows - 1][column - 1] == 1) {
+            return 0;
+        } else {
+            dp[0][0] = 1;
+        }
+        for (int i = 1; i < rows; i++) {
+            if (obstacleGrid[i][0] != 1) {
+                dp[i][0] = dp[i - 1][0];
+            }
+        }
+        for (int j = 1; j < column; j++) {
+            if (obstacleGrid[j][0] != 1) {
+                dp[0][j] = dp[0][j - 1];
+            }
+        }
+        for (int i = 1; i < rows; i++) {
+            for (int j = 1; j < column; j++) {
+                if (obstacleGrid[i][j] != 1) {
+                    dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
+                }
+            }
+        }
+        return dp[rows - 1][column - 1];
+    }
 }

main/test/dynamic_programming/LC_63_UniquePathsWithObstaclesTest.java

@@ -51,4 +51,21 @@ public void testUniquePathsWithObstaclesDP_Review() {
                 {{0, 0}, {1, 1}, {0, 0}}
         ), is(0));
     }
+
+    @Test
+    public void testUniquePathsWithObstaclesDP_3RD() {
+        assertThat(uniquePathsWithObstaclesDomain.uniquePathsWithObstaclesDP_3rd(new int[][]{
+                {0, 0, 0},
+                {0, 1, 0},
+                {0, 0, 0}
+        }), is(2));
+
+        assertThat(uniquePathsWithObstaclesDomain.uniquePathsWithObstaclesDP_3rd(new int[][]{
+                {1, 0}
+        }), is(0));
+
+        assertThat(uniquePathsWithObstaclesDomain.uniquePathsWithObstaclesDP_3rd(new int[][]
+                {{0, 0}, {1, 1}, {0, 0}}
+        ), is(0));
+    }
 }