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 由海洋逆推回到经过的坐标，用dfs方式将海洋逆推回去的坐标都设置为true，那么只要这个坐标能被太平洋和大西洋逆推为true，那么就添加到结果集中

class Solution {
private:void pacificAtlantic(vector<vector<int>>& heights,vector<vector<bool>>& visited,int x,int y){if(visited[x][y])return;else{visited[x][y]=true;if(y+1<heights[0].size()&&heights[x][y+1]>=heights[x][y])pacificAtlantic(heights,visited,x,y+1);if(x+1<heights.size()&&heights[x+1][y]>=heights[x][y])pacificAtlantic(heights,visited,x+1,y);if(y-1>=0&&heights[x][y-1]>=heights[x][y])pacificAtlantic(heights,visited,x,y-1);if(x-1>=0&&heights[x-1][y]>=heights[x][y])pacificAtlantic(heights,visited,x-1,y);}}
public:vector<vector<int>> pacificAtlantic(vector<vector<int>>& heights) {vector<vector<int>> result;int m=heights.size();int n=heights[0].size();vector<vector<bool>> pacific(m,vector<bool>(n,false));vector<vector<bool>> atlantic(m,vector<bool>(n,false));//分别将太平洋可达的坐标和大西洋可达的坐标都设置为truefor(int i=0;i<m;i++){pacificAtlantic(heights,pacific,i,0);pacificAtlantic(heights,atlantic,i,n-1);}for(int i=0;i<n;i++){pacificAtlantic(heights,pacific,0,i);pacificAtlantic(heights,atlantic,m-1,i);}//太平洋和大西洋都可达的加入到结果数组中for(int i=0;i<m;i++)for(int j=0;j<n;j++)if(pacific[i][j]&&atlantic[i][j])result.push_back({i,j});return result;}
};