C++二分算法：水位上升的泳池中游泳

class CUnionFind
{
public:
CUnionFind(int iSize) :m_vNodeToRegion(iSize)
{
for (int i = 0; i < iSize; i++)
{
m_vNodeToRegion[i] = i;
}
m_iConnetRegionCount = iSize;
}
int GetConnectRegionIndex(int iNode)
{
int& iConnectNO = m_vNodeToRegion[iNode];
if (iNode == iConnectNO)
{
return iNode;
}
return iConnectNO = GetConnectRegionIndex(iConnectNO);
}
void Union(int iNode1, int iNode2)
{
const int iConnectNO1 = GetConnectRegionIndex(iNode1);
const int iConnectNO2 = GetConnectRegionIndex(iNode2);
if (iConnectNO1 == iConnectNO2)
{
return;
}
m_iConnetRegionCount–;
if (iConnectNO1 > iConnectNO2)
{
UnionConnect(iConnectNO1, iConnectNO2);
}
else
{
UnionConnect(iConnectNO2, iConnectNO1);
}
}
bool IsConnect(int iNode1, int iNode2)
{
return GetConnectRegionIndex(iNode1) == GetConnectRegionIndex(iNode2);
}
int GetConnetRegionCount()const
{
return m_iConnetRegionCount;
}
vector GetNodeCountOfRegion()//各联通区域的节点数量
{
const int iNodeSize = m_vNodeToRegion.size();
vector vRet(iNodeSize);
for (int i = 0; i < iNodeSize; i++)
{
vRet[GetConnectRegionIndex(i)]++;
}
return vRet;
}
std::unordered_map<int, vector> GetNodeOfRegion()
{
std::unordered_map<int, vector> ret;
const int iNodeSize = m_vNodeToRegion.size();
for (int i = 0; i < iNodeSize; i++)
{
ret[GetConnectRegionIndex(i)].emplace_back(i);
}
return ret;
}
private:
void UnionConnect(int iFrom, int iTo)
{
m_vNodeToRegion[iFrom] = iTo;
}
vector m_vNodeToRegion;//各点所在联通区域的索引,本联通区域任意一点的索引，为了增加可理解性，用最小索引
int m_iConnetRegionCount;
};
class Solution {
public:
int swimInWater(vector<vector>& grid) {
m_c = grid.size();
int left = -1, right = m_c * m_c - 1;
while (right - left > 1)
{
const int mid = left + (right - left) / 2;
if (Can(grid, mid))
{
right = mid;
}
else
{
left = mid;
}
}
return right;
}
bool Can(const vector<vector>& grid, int t)
{
CUnionFind uf(m_c * m_c);
for (int r = 0; r < m_c; r++)
{
for (int c = 0; c < m_c; c++)
{
if (grid[r][c] > t)
{
continue;
}
if ((c+1<m_c)&&(grid[r][c + 1] <= t))
{
uf.Union(Mask(r,c), Mask(r, c+1));
}
if ((r + 1 < m_c) && (grid[r +1 ][c] <= t))
{
uf.Union(Mask(r, c), Mask(r + 1, c ));
}
}
}
return uf.IsConnect(0, m_c * m_c - 1);
}
int Mask(int r, int c)
{
return m_c * r + c;
}
int m_c;
};

template
void Assert(const T& t1, const T& t2)
{
assert(t1 == t2);
}
template
void Assert(const vector& v1, const vector& v2)
{
if (v1.size() != v2.size())
{
assert(false);
return;
}
for (int i = 0; i < v1.size(); i++)
{
Assert(v1[i], v2[i]);
}
}
int main()
{
vector<vector> grid;
int res = 0;
{
Solution slu;
grid = { {0,1,2,3,4},{24,23,22,21,5},{12,13,14,15,16},{11,17,18,19,20},{10,9,8,7,6} };
res = slu.swimInWater(grid);
Assert(16, res);
}
{
Solution slu;
grid = { {0,2},{1,3} };
res = slu.swimInWater(grid);
Assert(3, res);
}

class Solution {
public:
int swimInWater(vector<vector>& grid) {
m_r = grid.size();
m_c = grid[0].size();
int left = -1, right = 50 * 50 - 1;
while (right > left + 1)
{
const int iMid = left + (right - left) / 2;
if (CanVisit(grid, iMid))
{
right = iMid;
}
else
{
left = iMid;
}
}
return right;
}
bool CanVisit(const vector<vector>& vWater,int t)
{
vector<vector> vHasDo(m_r, vector(m_c));
std::queue<std::pair<int, int>> queRowCol;
Move(0, 0, vHasDo, queRowCol,vWater,t);
while (queRowCol.size())
{
const int r = queRowCol.front().first;
const int c = queRowCol.front().second;
queRowCol.pop();
if ((r + 1 == m_r) && (c + 1 == m_c))
{
return true;
}
Move(r+1, c, vHasDo, queRowCol, vWater,t);
Move(r-1, c, vHasDo, queRowCol, vWater,t);
Move(r, c+1, vHasDo, queRowCol, vWater,t);
Move(r, c-1, vHasDo, queRowCol, vWater,t);
}
return false;
}
void Move(int r, int c, vector<vector>& vHasDo, std::queue<std::pair<int, int>>& queRowCol, const vector<vector>& vWater,int t )
{
if ((r < 0) || (r >= m_r))
{
return;
}
if ((c < 0) || (c >= m_c))
{
return;
}
if (vWater[r][c] >t )
{
return;
}
if (vHasDo[r][c])
{
return;
}
vHasDo[r][c] = true;
queRowCol.emplace(r, c);
}
int m_r, m_c;
};