代码随想录算法训练营第39天 | 62. 不同路径、63. 不同路径 II

62. 不同路径

class Solution {
public:
    int uniquePaths(int m, int n) {
        vector> dp(m, vector(n, 0));
        for (int i = 0; i < m; i++) dp[i][0] = 1;
        for (int j = 0; j < n; j++) dp[0][j] = 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(vector>& obstacleGrid) {
        int m = obstacleGrid.size();
        int n = obstacleGrid[0].size();
        vector> dp(m, vector(n, 0));
        for (int j = 0; j < n; j++) {
            if (obstacleGrid[0][j] == 1) break;
            dp[0][j] = 1;
        }
        for (int i = 0; i < m; i++) {
            if (obstacleGrid[i][0] == 1) break;
            dp[i][0] = 1;
        }        
        for (int i = 1; i < m; i++) {
            for (int j = 1; j < n; j++) {
                if (obstacleGrid[i][j] == 1) continue;
                dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
            }
        }
        return dp[m - 1][n - 1];
    }
};