63. Unique Paths II

class Solution {
public int uniquePathsWithObstacles(int[][] obstacleGrid) {
for(int i=0;i<obstacleGrid.length;i++)
for(int j=0;j<obstacleGrid[0].length;j++)
obstacleGrid[i][j]=-obstacleGrid[i][j];
obstacleGrid[0][0]=obstacleGrid[0][0]>=0?1:0;
for(int i=0;i<obstacleGrid.length;i++)
for(int j=0;j<obstacleGrid[0].length;j++)
if(obstacleGrid[i][j]>=0)
obstacleGrid[i][j]+=(i>0&&obstacleGrid[i-1][j]>=0?obstacleGrid[i-1][j]:0)+(j>0&&obstacleGrid[i][j-1]>=0?obstacleGrid[i][j-1]:0);
return Math.max(obstacleGrid[obstacleGrid.length-1][obstacleGrid[0].length-1], 0);
}
}