leetcode(c++)岛屿问题

#include <iostream>
#include <vector>
#include <queue>
#include <filesystem>
#include <stdio.h>
#include <string>
#include <stack>

using namespace std;

void print(vector<vector<string>>& grid)
{
    for(const auto& g:grid)
    {
        for(const auto& i:g)
        {
            cout << i << " ";
        }
        cout << endl;
    }
}

void dfs(vector<vector<string>>&grid,int i, int j)
{
    if(i < 0 || i >= grid.size() || j < 0 || j >= grid[0].size() || grid[i][j] == "0")
        return ;
    grid[i][j] = "0";
    dfs(grid,i-1,j);
    dfs(grid,i+1,j);
    dfs(grid,i,j-1);
    dfs(grid,i,j+1);
    return;
}

vector<pair<int,int>>dirs{{0,-1},{0,1},{1,0},{-1,0}};

class DSU{
    vector<int>parent_;
    public:
    DSU(int N)
    {
        parent_.resize(N);
        for(int i = 0; i < N; ++i)
        {
            parent_[i] = i;
        }
    }
    int find(int x)
    {
        if(parent_[x] != x)parent_[x] = find(parent_[x]);
        return parent_[x];
    }
    void Union(int x, int y)
    {
        parent_[find(x)] = find(y);
    }
};

void bfs(vector<vector<string>>& grid, int i ,int j)
{
    queue<pair<int,int>>q;
    q.push({i,j});
    while(!q.empty())
    {
        auto cur = q.front();
        q.pop();
        int x = cur.first,y = cur.second;
        if(x < 0 || x >= grid.size() || y < 0 || y >= grid[0].size() || grid[x][y] == "0")continue;
        grid[x][y] = "0";
        for(auto dir:dirs)
        {
            q.push({x+dir.first,y+dir.second});
        }
    }
}

void dfs_stack(vector<vector<string>>&grid,int i,int j)
{
    stack<pair<int,int>>st;
    st.push({i,j});
    while(!st.empty())
    {
        auto cur = st.top();
        st.pop();
        int x = cur.first, y = cur.second;
        if(x < 0 || x >= grid.size() || y < 0 || y >= grid[0].size() || grid[x][y] == "0")continue;
        grid[x][y] = "0";
        for(auto p:dirs)
        {
            st.push({x + p.first,y+p.second});
        }
    }
}

int numIslands(vector<vector<string>>&grid)
{
    int m = grid.size(), n = grid[0].size(),res = 0;
    DSU dsu(m*n);

    for(int i = 0; i < m ;++i)
    {
        for(int j = 0; j < n; ++j)
        {
            if(grid[i][j] == "1")
            {
                ++res;
                dfs_stack(grid,i,j);
//                bfs(grid,i,j);
//                dfs(grid,i,j);
//                DSU
//                for(const pair<int,int>p:dirs)
//                {
//                    int x = i + p.first, y = j + p.second;
//                    if(x >= 0 && y >= 0 && x < m && y < n && grid[x][y] == "1")
//                    {
//                        if(dsu.find(x*n+y)!=dsu.find(i*n+j)) --res;
//                        dsu.Union(x*n+y,i*n+j);
//                    }
//                }
            }
        }
    }
    return res;
}

void dfs(vector<vector<string>>&grid,int i,int j, vector<int>&area)
{
    if(i < 0 || i >=grid.size()||j < 0 || j >= grid[0].size()|| grid[i][j] == "0")return;
    grid[i][j] = "0";
    ++area[0];
    dfs(grid,i-1,j,area);
    dfs(grid,i+1,j,area);
    dfs(grid,i,j-1,area);
    dfs(grid,i,j+1,area);
    return ;
}

int maxAreaOfIsland(vector<vector<string>>& grid)
{
    int m  = grid.size(), n = grid[0].size();
    int res = 0;
    vector<int>area(1);
    for(int i = 0;i < m; ++i)
    {
        for(int j = 0; j < n; ++j)
        {
            if(grid[i][j] == "1")
            {
                area[0] = 0;
                dfs(grid,i,j,area);
                res = max(res,area[0]);
            }
        }
    }
    return res;
}

int dfs0(vector<vector<string>>&grid,int i, int j)
{
    if(i <0 || i >= grid.size() || j < 0 || j >= grid[0].size() || grid[i][j] == "0")return 1;
    if(grid[i][j] == ".")return 0;
    grid[i][j] = ".";
    return dfs0(grid,i-1,j)+dfs0(grid,i+1,j)+dfs0(grid,i,j-1)+dfs0(grid,i,j+1);
}

int islandPerimeter(vector<vector<string>>&grid)
{
    int m = grid.size(), n = grid[0].size();
    for(int i = 0;i < m; ++i)
    {
        for(int j = 0;j < n ;++j)
        {
            if(grid[i][j] == "1")
            {
                return dfs0(grid,i,j);
            }
        }
    }
}

bool dfs(vector<vector<string>>&grid,int i, int j, int m,int n)
{
    if(i < 0 || j < 0 || i >= m || j >= n) return false;
    if(grid[i][j] == "0")return true;
    grid[i][j] = "0";
    return dfs(grid,i+1,j,m,n) &&dfs(grid,i-1,j,m,n) && dfs(grid,i,j-1,m,n) && dfs(grid,i,j+1,m,n);
}

int closeIsland(vector<vector<string>>&grid)
{
    int res = 0, m = grid.size(), n = grid[0].size();
    for(int i = 0; i < m; ++i)
    {
        for(int j = 0;j < n ; ++j)
        {
            if(grid[i][j] == "1" && dfs(grid,i,j,m,n)) ++res;

        }
    }
    return res;
}

int main()
{

//    vector<vector<string>>grid{{"1","1","1","1","0"},{"1","1","0","1","0"},{"1","1","0","0","0"},{"0","0","0","0","0"}};
//    vector<vector<string>>grid{{"1","1","0","0","0"},{"1","1","0","0","0"},{"0","0","1","0","0"},{"0","0","0","1","1"}};
//    vector<vector<string>>grid{{"0","1","0","0"},{"1","1","1","0"},{"0","1","0","0"},{"1","1","0","0"}};
    vector<vector<string>>grid{{"1","1","0","1","1"},{"1","0","1","0","1"},{"1","0","0","0","1"}};
    print(grid);
//    LeetCode200
//    cout << numIslands(grid)<<endl;

//    LeetCode695
//    cout << maxAreaOfIsland(grid)<<endl;

    //LeetCode463
//    cout << islandPerimeter(grid)<<endl;

//    LeetCode1254

    cout << closeIsland(grid) <<endl;


    return 0;
}