63. 不同路径 II

package leetcode;

public class LeetCode {
    public static void main(String[] args) {
        System.out.println(new Solution().uniquePathsWithObstacles(new int[][] {new int[] {0, 0, 0}, new int[] {0, 1, 0}, new int[] {0, 0, 0}}));
    }
}

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 && obstacleGrid[i][0] == 0; i++) {
            dp[i][0] = 1;
        }

        for (int i = 0; i < n && obstacleGrid[0][i] == 0; i++) {
            dp[0][i] = 1;
        }

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

        return dp[m - 1][n - 1];
    }
}

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