diff --git a/problems/0062.不同路径.md b/problems/0062.不同路径.md index 2367587c..4c0e2279 100644 --- a/problems/0062.不同路径.md +++ b/problems/0062.不同路径.md @@ -436,6 +436,26 @@ int uniquePaths(int m, int n){ } ``` +滚动数组解法: +```c +int uniquePaths(int m, int n){ + int i, j; + + // 初始化dp数组 + int *dp = (int*)malloc(sizeof(int) * n); + for (i = 0; i < n; ++i) + dp[i] = 1; + + for (j = 1; j < m; ++j) { + for (i = 1; i < n; ++i) { + // dp[i]为二维数组解法中dp[i-1][j]。dp[i-1]为二维数组解法中dp[i][j-1] + dp[i] += dp[i - 1]; + } + } + return dp[n - 1]; +} +``` + ### Scala ```scala diff --git a/problems/0063.不同路径II.md b/problems/0063.不同路径II.md index 9aa36956..b89486e6 100644 --- a/problems/0063.不同路径II.md +++ b/problems/0063.不同路径II.md @@ -539,6 +539,39 @@ int uniquePathsWithObstacles(int** obstacleGrid, int obstacleGridSize, int* obst } ``` +空间优化版本: +```c +int uniquePathsWithObstacles(int** obstacleGrid, int obstacleGridSize, int* obstacleGridColSize){ + int m = obstacleGridSize; + int n = obstacleGridColSize[0]; + int *dp = (int*)malloc(sizeof(int) * n); + int i, j; + + // 初始化dp为第一行起始状态。 + for (j = 0; j < n; ++j) { + if (obstacleGrid[0][j] == 1) + dp[j] = 0; + else if (j == 0) + dp[j] = 1; + else + dp[j] = dp[j - 1]; + } + + for (i = 1; i < m; ++i) { + for (j = 0; j < n; ++j) { + if (obstacleGrid[i][j] == 1) + dp[j] = 0; + // 若j为0,dp[j]表示最左边一列,无需改动 + // 此处dp[j],dp[j-1]等同于二维dp中的dp[i-1][j]和dp[i][j-1] + else if (j != 0) + dp[j] += dp[j - 1]; + } + } + + return dp[n - 1]; +} +``` + ### Scala ```scala