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leetcode--Unique Paths II

2024-07-07 09:39:22   226人阅读

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.

?
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public class Solution {
    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
        int path = 0;
        int row = obstacleGrid.length;
        if(row > 0){
            int column = obstacleGrid[0].length;
            int[][] paths = new int[row][column];
            if(obstacleGrid[0][0] != 1){
                paths[0][0] = 1;
                for(int i = 1; i < row; ++i){
                    if(obstacleGrid[i][0] != 1)
                        paths[i][0] = paths[i - 1][0];
                    else
                        paths[i][0] = 0;
                }
                for(int i = 1; i < column; ++i){
                    if(obstacleGrid[0][i] != 1)
                        paths[0][i] = paths[0][i - 1];
                    else
                        paths[0][i] = 0;
                }
                 
                for(int i = 1; i < row; ++i){
                    for(int j = 1; j < column; ++j){
                        if(obstacleGrid[i][j] != 1)
                            paths[i][j] = paths[i - 1][j] + paths[i][j - 1];
                        else
                            paths[i][j] = 0;
                    }
                }
                path = paths[row - 1][column - 1];
            }
        }
        return path;   
    }
}

　　


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