<p>You are given an <code>m x n</code> integer array <code>grid</code>. There is a robot initially located at the <b>top-left corner</b> (i.e., <code>grid[0][0]</code>). The robot tries to move to the <strong>bottom-right corner</strong> (i.e., <code>grid[m - 1][n - 1]</code>). The robot can only move either down or right at any point in time.</p>

<p>An obstacle and space are marked as <code>1</code> or <code>0</code> respectively in <code>grid</code>. A path that the robot takes cannot include <strong>any</strong> square that is an obstacle.</p>

<p>Return <em>the number of possible unique paths that the robot can take to reach the bottom-right corner</em>.</p>

<p>The testcases are generated so that the answer will be less than or equal to <code>2 * 10<sup>9</sup></code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/11/04/robot1.jpg" style="width: 242px; height: 242px;" />
<pre>
<strong>Input:</strong> obstacleGrid = [[0,0,0],[0,1,0],[0,0,0]]
<strong>Output:</strong> 2
<strong>Explanation:</strong> There is one obstacle in the middle of the 3x3 grid above.
There are two ways to reach the bottom-right corner:
1. Right -&gt; Right -&gt; Down -&gt; Down
2. Down -&gt; Down -&gt; Right -&gt; Right
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/11/04/robot2.jpg" style="width: 162px; height: 162px;" />
<pre>
<strong>Input:</strong> obstacleGrid = [[0,1],[0,0]]
<strong>Output:</strong> 1
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>m == obstacleGrid.length</code></li>
	<li><code>n == obstacleGrid[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 100</code></li>
	<li><code>obstacleGrid[i][j]</code> is <code>0</code> or <code>1</code>.</li>
</ul>

class Solution {
public:
    
    int isPossible(int i,int j, int m, int n,int obst){
        if(i>=0&&i<m&&j>=0&&j<n&&!obst){
            return 1; 
        }
        return 0;
    }

    
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        int m=obstacleGrid.size();
        int n=obstacleGrid[0].size();

        int dp[m][n];

        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                dp[i][j]=0;
            }
        }
        if(!obstacleGrid[0][0]) dp[0][0]=1;
        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                if(isPossible(i-1,j,m,n,obstacleGrid[i][j])) dp[i][j]+=dp[i-1][j];
                if(isPossible(i,j-1,m,n,obstacleGrid[i][j])) dp[i][j]+=dp[i][j-1];
            }
        }
        return dp[m-1][n-1];
    }
};
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