62.不同路径 

62. 不同路径 - 力扣（LeetCode）

class Solution {public int uniquePaths(int m, int n) {//1dp数组  m n代表位置，dp[m][n]代表到达这里的途径个数int [][] dp = new int[m][n];//3初始化for(int i = 0;i<n;i++){dp[0][i] = 1;}for(int j = 0;j<m;j++){dp[j][0] = 1;}//4遍历顺序for(int i = 1;i<m;i++){for(int j = 1;j<n;j++){//2递推公式dp[i][j] = dp[i-1][j]+dp[i][j-1]; }}return dp[m-1][n-1];}
}

 63. 不同路径 II 

63. 不同路径 II - 力扣（LeetCode）

class Solution {public int uniquePathsWithObstacles(int[][] obstacleGrid) {int m = obstacleGrid.length;int n = obstacleGrid[0].length;int [][] dp = new int [m][n];//如果在起点或终点出现了障碍，直接返回0if (obstacleGrid[m - 1][n - 1] == 1 || obstacleGrid[0][0] == 1) {return 0;}for(int i = 0;i<n;i++){if(obstacleGrid[0][i]==1){break;}dp[0][i]=1;}for(int j=0;j<m;j++){if(obstacleGrid[j][0]==1) break;dp[j][0] = 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];}
}