This commit is contained in:
krahets
2024-05-06 14:40:36 +08:00
parent 7e7eb6047a
commit 5c7d2c7f17
54 changed files with 3456 additions and 215 deletions

View File

@@ -133,7 +133,22 @@ Implementation code as follows:
=== "C++"
```cpp title="min_path_sum.cpp"
[class]{}-[func]{minPathSumDFS}
/* Minimum path sum: Brute force search */
int minPathSumDFS(vector<vector<int>> &grid, int i, int j) {
// If it's the top-left cell, terminate the search
if (i == 0 && j == 0) {
return grid[0][0];
}
// If the row or column index is out of bounds, return a +∞ cost
if (i < 0 || j < 0) {
return INT_MAX;
}
// Calculate the minimum path cost from the top-left to (i-1, j) and (i, j-1)
int up = minPathSumDFS(grid, i - 1, j);
int left = minPathSumDFS(grid, i, j - 1);
// Return the minimum path cost from the top-left to (i, j)
return min(left, up) != INT_MAX ? min(left, up) + grid[i][j] : INT_MAX;
}
```
=== "Java"
@@ -264,7 +279,27 @@ We introduce a memo list `mem` of the same size as the grid `grid`, used to reco
=== "C++"
```cpp title="min_path_sum.cpp"
[class]{}-[func]{minPathSumDFSMem}
/* Minimum path sum: Memoized search */
int minPathSumDFSMem(vector<vector<int>> &grid, vector<vector<int>> &mem, int i, int j) {
// If it's the top-left cell, terminate the search
if (i == 0 && j == 0) {
return grid[0][0];
}
// If the row or column index is out of bounds, return a +∞ cost
if (i < 0 || j < 0) {
return INT_MAX;
}
// If there is a record, return it
if (mem[i][j] != -1) {
return mem[i][j];
}
// The minimum path cost from the left and top cells
int up = minPathSumDFSMem(grid, mem, i - 1, j);
int left = minPathSumDFSMem(grid, mem, i, j - 1);
// Record and return the minimum path cost from the top-left to (i, j)
mem[i][j] = min(left, up) != INT_MAX ? min(left, up) + grid[i][j] : INT_MAX;
return mem[i][j];
}
```
=== "Java"
@@ -394,7 +429,28 @@ Implement the dynamic programming solution iteratively, code as shown below:
=== "C++"
```cpp title="min_path_sum.cpp"
[class]{}-[func]{minPathSumDP}
/* Minimum path sum: Dynamic programming */
int minPathSumDP(vector<vector<int>> &grid) {
int n = grid.size(), m = grid[0].size();
// Initialize dp table
vector<vector<int>> dp(n, vector<int>(m));
dp[0][0] = grid[0][0];
// State transition: first row
for (int j = 1; j < m; j++) {
dp[0][j] = dp[0][j - 1] + grid[0][j];
}
// State transition: first column
for (int i = 1; i < n; i++) {
dp[i][0] = dp[i - 1][0] + grid[i][0];
}
// State transition: the rest of the rows and columns
for (int i = 1; i < n; i++) {
for (int j = 1; j < m; j++) {
dp[i][j] = min(dp[i][j - 1], dp[i - 1][j]) + grid[i][j];
}
}
return dp[n - 1][m - 1];
}
```
=== "Java"
@@ -563,7 +619,27 @@ Please note, since the array `dp` can only represent the state of one row, we ca
=== "C++"
```cpp title="min_path_sum.cpp"
[class]{}-[func]{minPathSumDPComp}
/* Minimum path sum: Space-optimized dynamic programming */
int minPathSumDPComp(vector<vector<int>> &grid) {
int n = grid.size(), m = grid[0].size();
// Initialize dp table
vector<int> dp(m);
// State transition: first row
dp[0] = grid[0][0];
for (int j = 1; j < m; j++) {
dp[j] = dp[j - 1] + grid[0][j];
}
// State transition: the rest of the rows
for (int i = 1; i < n; i++) {
// State transition: first column
dp[0] = dp[0] + grid[i][0];
// State transition: the rest of the columns
for (int j = 1; j < m; j++) {
dp[j] = min(dp[j - 1], dp[j]) + grid[i][j];
}
}
return dp[m - 1];
}
```
=== "Java"