之前写过一个类似的，这种回溯的其实并不用对sum进行设置：
class Solution {int ml = 0;private void dfs(int[][] grid, int i, int j, boolean sign[][], int sum){ml = Math.max(ml, sum);// 如果出界if(i < 0 || j < 0 || i == grid.length || j == grid[0].length){return;}// 如果没有黄金if(grid[i][j] == 0){return;}// 如果遍历过if(sign[i][j]){return;}// 否则sign[i][j] = true;dfs(grid, i+1, j, sign, sum+grid[i][j]);dfs(grid, i, j+1, sign, sum+grid[i][j]);dfs(grid, i-1, j, sign, sum+grid[i][j]);dfs(grid, i, j-1, sign, sum+grid[i][j]);sign[i][j] = false;}public int getMaximumGold(int[][] grid) {int rows = grid.length;int columns = grid[0].length;boolean sign[][] = new boolean[grid.length][grid[0].length];for(int i=0; i<rows; i++){for(int j=0; j<columns; j++){if(grid[i][j] != 0){dfs(grid, i, j, sign, 0);}}}return ml;}public static void main(String[] args) {Solution s = new Solution();s.getMaximumGold(new int[][]{{1,0,7},{2,0,6},{3,4,5},{0,3,0},{9,0,20}});}
}
