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