62. 不同路径

class Solution {
    public int uniquePaths(int m, int n) {
        int[][] dp = new int[m][n];
        for(int i = 0;i < m;i++){
            dp[i][0] = 1;
        }
        for(int i = 0;i < n;i++){
            dp[0][i] = 1;
        }
        for(int i = 1;i < m;i++){
            for(int j = 1;j < n;j++){
                dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
            }
        }
        return dp[m - 1][n - 1];
    }
}

63. 不同路径 II

class Solution {
    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
        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] == 0){
                dp[i][0] = 1;
            }else{
                break;
            }
        }
        for(int i = 0;i < n;i++){
            if(obstacleGrid[0][i] == 0){
                dp[0][i] = 1;
            }else{
                break;
            }
        }
        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];
    }
}