floodfill篇
cpp
unordered_multimap<int, int> direction = {
{0, 1},
{0, -1},
{1, 0},
{-1, 0}
};
void dfs(vector<vector<int>>& image, int sr, int sc, int color, int val)
{
image[sr][sc] = color;
for(auto& e : direction)
{
int x = sr + e.first, y = sc + e.second;
if((x >= 0 && x < image.size())
&& (y >= 0 && y < image[0].size())
&& (image[x][y] == val))
{
dfs(image, x, y, color, val);
}
}
}
vector<vector<int>> floodFill(vector<vector<int>>& image, int sr, int sc, int color)
{
if(color == image[sr][sc]) return image;
dfs(image, sr, sc, color, image[sr][sc]);
return image;
}
cpp
unordered_multimap<int, int> direction = {
{0, 1},
{0, -1},
{1, 0},
{-1, 0}
};
void dfs(vector<vector<char>>& grid, vector<vector<bool>>& visit, int i, int j)
{
visit[i][j] = true;
for(auto& e : direction)
{
int x = i + e.first, y = j + e.second;
if((x >= 0 && x < grid.size())
&& (y >= 0 && y < grid[0].size())
&& (grid[x][y] == '1')
&& (visit[x][y] == false))
{
dfs(grid, visit, x, y);
}
}
}
int numIslands(vector<vector<char>>& grid)
{
vector<vector<bool>> visit(grid.size(), vector<bool>(grid[0].size()));
int ret = 0;
for(int i = 0; i < grid.size(); ++i)
{
for(int j = 0; j < grid[0].size(); ++j)
{
if(grid[i][j] == '1' && visit[i][j] == false)
{
ret += 1;
dfs(grid, visit, i, j);
}
}
}
return ret;
}
cpp
int area = 0;
unordered_multimap<int, int> direction = {
{0, 1},
{0, -1},
{1, 0},
{-1, 0}
};
void dfs(vector<vector<int>>& grid, vector<vector<bool>>& visit, int i, int j)
{
++area;
visit[i][j] = true;
for(auto& e : direction)
{
int x = i + e.first, y = j + e.second;
if((x >= 0 && x < grid.size())
&& (y >= 0 && y < grid[0].size())
&& (grid[x][y] == 1)
&& (visit[x][y] == false))
{
dfs(grid, visit, x, y);
}
}
}
int maxAreaOfIsland(vector<vector<int>>& grid)
{
vector<vector<bool>> visit(grid.size(), vector<bool>(grid[0].size()));
int ret = 0;
for(int i = 0; i < grid.size(); ++i)
{
for(int j = 0; j < grid[0].size(); ++j)
{
if(grid[i][j] == 1 && visit[i][j] == false)
{
dfs(grid, visit, i, j);
if(area > ret) ret = area;
area = 0;
}
}
}
return ret;
}
cpp
unordered_multimap<int, int> direction = {
{0, 1},
{0, -1},
{1, 0},
{-1, 0}
};
void dfs(vector<vector<char>>& board, vector<vector<bool>>& visit, int i, int j)
{
visit[i][j] = true;
for(auto& e : direction)
{
int x = i + e.first, y = j + e.second;
if((x >= 0 && x < board.size())
&& (y >= 0 && y < board[0].size())
&& (board[x][y] == 'O')
&& (visit[x][y] == false))
{
dfs(board, visit, x, y);
}
}
}
void solve(vector<vector<char>>& board)
{
vector<vector<bool>> visit(board.size(), vector<bool>(board[0].size(), false));
// 第一行 i=0
for(int j = 0; j < board[0].size(); ++j)
{
if(board[0][j] == 'O' && visit[0][j] == false)
{
dfs(board, visit, 0, j);
}
}
// 最后一行 i=board.size()-1
for(int j = 0; j < board[0].size(); ++j)
{
if(board[board.size()-1][j] == 'O' && visit[board.size()-1][j] == false)
{
dfs(board, visit, board.size() - 1, j);
}
}
// 第一列 j=0
for(int i = 1; i < board.size() - 1; ++i)
{
if(board[i][0] == 'O' && visit[i][0] == false)
{
dfs(board, visit, i, 0);
}
}
// 最后一列 j=board[0].size() - 1
for(int i = 1; i < board.size() - 1; ++i)
{
if(board[i][board[0].size() - 1] == 'O' && visit[i][board[0].size() - 1] == false)
{
dfs(board, visit, i, board[0].size() - 1);
}
}
for(int i = 0; i < board.size(); ++i)
{
for(int j = 0; j < board[0].size(); ++j)
{
if(board[i][j] == 'O' && visit[i][j] == false)
{
board[i][j] = 'X';
}
}
}
}
cpp
unordered_multimap<int, int> direction = {
{0, 1},
{0, -1},
{1, 0},
{-1, 0}
};
int m, n;
void dfs(vector<vector<int>>& heights, vector<vector<bool>>& visit, int i , int j)
{
visit[i][j] = true;
for(auto& e : direction)
{
int x = i + e.first, y = j + e.second;
if((x >= 0 && x < m)
&& (y >= 0 && y < n)
&& (heights[i][j] <= heights[x][y])
&& (visit[x][y] == false))
{
dfs(heights, visit, x, y);
}
}
}
vector<vector<int>> pacificAtlantic(vector<vector<int>>& heights)
{
m = heights.size();
n = heights[0].size();
vector<vector<bool>> visit1(m, vector<bool>(n, false));
vector<vector<bool>> visit2(m, vector<bool>(n, false));
// 第一行 i=0
for(int j = 0; j < n; ++j)
{
if(visit1[0][j] == false)
{
dfs(heights, visit1, 0, j);
}
}
// 第一列 j=0
for(int i = 0; i < m; ++i)
{
if(visit1[i][0] == false)
{
dfs(heights, visit1, i, 0);
}
}
// 最后一行 i=m-1
for(int j = 0; j < n; ++j)
{
if(visit2[m-1][j] == false)
{
dfs(heights, visit2, m-1, j);
}
}
// 最后一列 j=n-1
for(int i = 0; i < m; ++i)
{
if(visit2[i][n-1] == false)
{
dfs(heights, visit2, i, n-1);
}
}
vector<vector<int>> ret;
for(int i = 0; i < m; ++i)
{
for(int j = 0; j < n; ++j)
{
if(visit1[i][j] && visit2[i][j])
{
ret.push_back({i, j});
}
}
}
return ret;
}
cpp
unordered_multimap<int, int> direction = {
{-1, -1},
{-1, 0},
{-1, 1},
{0, -1},
{0, 1},
{1, -1},
{1, 0},
{1, 1}
};
void dfs(vector<vector<char>>& board, int i, int j)
{
char ch = '0';
for(auto& e : direction)
{
int x = i + e.first, y = j + e.second;
if((x >= 0 && x < board.size())
&& (y >= 0 && y < board[0].size())
&& (board[x][y] == 'M'))
++ch;
}
if(ch > '0')
{
board[i][j] = ch;
return;
}
board[i][j] = 'B';
for(auto& e : direction)
{
int x = i + e.first, y = j + e.second;
if((x >= 0 && x < board.size())
&& (y >= 0 && y < board[0].size())
&& (board[x][y] == 'E'))
dfs(board, x, y);
}
}
vector<vector<char>> updateBoard(vector<vector<char>>& board, vector<int>& click)
{
int r = click[0], c = click[1];
if(board[r][c] != 'M' && board[r][c] != 'E') return board;
if(board[r][c] == 'M')
{
board[r][c] = 'X';
return board;
}
// board[r][c]是未挖出的的空方块 - 'E'
dfs(board, r, c);
return board;
}
cpp
int ret = 0;
unordered_multimap<int, int> direction = {
{0, 1},
{0, -1},
{1, 0},
{1, -1}
};
int digit(int x)
{
int sum = 0;
while(x)
{
sum += (x % 10);
x /= 10;
}
return sum;
}
void dfs(vector<vector<bool>>& visit, int i, int j, int cnt)
{
++ret;
visit[i][j] = true;
for(auto& e : direction)
{
int x = i + e.first, y = j + e.second;
if((x >= 0 && x < visit.size())
&& (y >= 0 && y < visit[0].size())
&& (visit[x][y] == false)
&& ((digit(x) + digit(y) <= cnt)))
{
dfs(visit, x, y, cnt);
}
}
}
int wardrobeFinishing(int m, int n, int cnt)
{
vector<vector<bool>> visit(m, vector<bool>(n, false));
dfs(visit, 0, 0, cnt);
return ret;
}