"Leetcode-Interview algorithm classic-java Implementation" "064-minimum path Sum (minimum path and)"

"064-minimum path Sum (minimum path and)" "leetcode-Interview algorithm classic-java Implementation" "All topics Directory Index" Original Question

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of All numbers along its path.
　　Note: You can only move either down or right at any point in time.

Main Topic

Given a square of M x N, each element's value is nonnegative, finding the path from the top-left vertex to the lower-right vertex and the lowest value, returning the smallest and found.

Thinking of solving problems

Divide and conquer the law,
First: s[0][0] = grid[0][0]
First line: s[0][j] = s[0][j-1] + grid[0][j]
First column: s[i][0] = s[i-1][0] + grid[i][0]
Other cases: s[i][j] = min (S[i-1][j], s[i][j-1]) + grid[i][j]

Code Implementation

Algorithm implementation class

 Public classSolution { Public int Minpathsum(int[] grid) {//parameter checking        if(Grid = =NULL|| Grid.length <1|| grid[0].length <1) {return 0; }int[[] result =New int[Grid.length] [grid[0].length];//Firstresult[0][0] = grid[0][0];//First line         for(inti =1; I < result[0].length; i++) {result[0][i] = result[0][i-1] + grid[0][i]; }//First column         for(inti =1; i < result.length; i++) {result[i][0] = Result[i-1][0] + grid[i][0]; }//Other conditions         for(inti =1; i < result.length; i++) { for(intj =1; J < result[0].length; J + +) {Result[i][j] = math.min (Result[i-1][J], Result[i][j-1]) + grid[i][j]; }        }returnResult[result.length-1][result[0].length-1]; }////////////////////////////////////////////////////////////////////////////////////////////////    //dynamic attribution and branching, the following method will time out    ////////////////////////////////////////////////////////////////////////////////////////////////     Public int minPathSum2(int[] grid) {//parameter checking        if(Grid = =NULL|| Grid.length <1|| grid[0].length <1) {return 0; }//Used to record the smallest path        int[] Minsum = {Integer.max_value};int[] Cursum = {0};//SolvingSolve (grid,0,0, Cursum, minsum);//Return results        returnminsum[0]; } Public void Solve(int[] Grid,intRowintColint[] Cursum,int[] minsum) {//If you have reached the end        if(Row = = Grid.length-1&& col = = grid[0].length-1) {cursum[0] + = Grid[row][col];//Update the minimum and            if(cursum[0] < minsum[0]) {minsum[0] = cursum[0]; } cursum[0]-= Grid[row][col]; }//has not reached the end point and is within the grid        Else if(Row >=0&& Row < grid.length && Col >=0&& Col < grid[0].length) {cursum[0] + = Grid[row][col];//current and only minimum path values not less than recorded to proceed to the next steps            if(cursum[0] <= minsum[0]) {//GO rightSolve (grid, row, col +1, Cursum, minsum);//Go downSolve (grid, row +1, col, Cursum, minsum); } cursum[0]-= Grid[row][col]; }    }}

Evaluation Results

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"Leetcode-Interview algorithm classic-java Implementation" "064-minimum path Sum (minimum path and)"