LeetCode: Unique Paths II 解题报告

Unique Paths II

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Question Solution 

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.

SOULUTION 1:

跟LeetCode: Unique Paths 解题报告 相比，只不过是判断一下当前是不是block，如果是block,直接设置D[i][j] 是0就好了 也就是不可达。 同样在3分钟之内Bug free 秒答，哦耶！

 public class Solution {
     public int uniquePathsWithObstacles(int[][] obstacleGrid) {
         //
         if (obstacleGrid == null || obstacleGrid.length ==  || obstacleGrid[].length == ) {
             return ;
         }

         int rows = obstacleGrid.length;
         int cols = obstacleGrid[].length;

         int[][] D = new int[rows][cols];

         for (int i = ; i < rows; i++) {
             for (int j = ; j < cols; j++) {
                 D[i][j] = ;
                 if (obstacleGrid[i][j] == ) {
                     D[i][j] = ;
                 } else {
                     if (i ==  && j == ) {
                         D[i][j] = ;
                     }

                     if (i != ) {
                         D[i][j] += D[i - ][j];
                     }

                     if (j != ) {
                         D[i][j] += D[i][j - ];
                     }
                 }
             }
         }

         return D[rows - ][cols - ];
     }
 }