[Leetcode] [Java] Unique Paths II

Title:

Follow up for "Unique Paths":

Now consider if some obstacles is added to the grids. How many unique paths would there be?

An obstacle and empty space are marked as and respectively in the 1 0 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 would be is at most 100.

Test Instructions:

followed by the topic "Unique Paths", now gives the topic:

If you add some obstacles to the lattice, how many existing and unique paths will appear?

Barriers and blank squares are labeled and 1 0 .

For example , there is a barrier in the middle of a 3x3 lattice, as shown below:

[  [0,0,0],  [0,1,0],  [0,0,0]

The total number of paths is 2.

Algorithm Analysis:

The idea is similar to the topic "Unique Paths", where the difference is:

An obstacle occurs when initializing boundary upstream and columns, and the number of subsequent paths DP is 0

When an obstacle occurs in the middle lattice, the number of paths represented by the grid DP is directly filled in 0

AC Code:

public class Solution {public    int uniquepathswithobstacles (int[][] obstaclegrid)     {        if (obstaclegrid== null| | obstaclegrid.length==0)        return 0;    int m = obstaclegrid.length;        int n = obstaclegrid[0].length;    int [] [] DP = new Int[m][n];        for (int i = 0; i < m; i++)        {            if (obstaclegrid[i][0]!=1)            dp[i][0] = 1;            else break             ;        }        for (int j = 0; J < N; j + +)        {        if (obstaclegrid[0][j]!=1)        dp[0][j] = 1;        else break         ;        }        for (int i = 1, i < m; i++)        {for            (int j = 1; j< N; j + +)            {            if (obstaclegrid[i][j]!=1)            Dp[i][j] = Dp[i-1][j] + dp[i][j-1];            else            dp[i][j]=0;            }        }        return dp[m-1][n-1];}    }

Copyright NOTICE: This article is the original article of Bo Master, reprint annotated source

[Leetcode][java] Unique Paths II