【代码随想录Day39动态规划part02】62.不同路径、63.不同路径Ⅱ

Day39

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