Ptr getMaxTree(const Arr<T>& data) {
if (data.empty()) return nullptr;
Arr<Ptr> node(data.size(), nullptr);
for(int i = 0; i < data.size(); ++i)
node[i] = std::make_shared<TreeNode>(data[i]);
HashMap MaxMap;
std::stack<Ptr> s;
for (int i = 0; i < data.size(); ++i) {
auto cur = node[i];
while (!s.empty() && s.top()->value < data[i]) {
popStackSetMap(s, MaxMap, cur);
}
s.push(node[i]);
}
while (!s.empty()) {
popStackSetMap(s, MaxMap, nullptr);
}
Ptr head = nullptr;
for (int i = 0; i < node.size(); ++i) {
auto cur = node[i];
auto res = MaxMap.find(cur);
//结构如下 node left right
//node是当前访问节点 left是左边离他最近比node大的点，right是右边。。
//nullptr代表没有或者到达边界
if (!res->second.first && !res->second.second) {
head = res->first;
}
else if (!res->second.first) {
if (!res->second.second->left) {
res->second.second->left = res->first;
}
else {
res->second.second->right = res->first;
}
}
else if (!res->second.second) {
if (!res->second.first->left) {
res->second.first->left = res->first;
}
else {
res->second.first->right = res->first;
}
}
else {
auto tmp = res->second.first->value < res->second.second->value ? res->second.first : res->second.second;
if (!tmp->left) {
tmp->left = res->first;
}
else {
tmp->right = res->first;
}
}
}
return head;
}
std::pair<int, int> getMinMax(const Arr& data) {
int maxNum = INT_MIN;
int minNum = INT_MAX;
if (data.size() & 0x1)
maxNum = minNum = data.back();
for (int i = 0; i + 1< data.size(); i+=2) {
if (data[i] < data[i + 1]) {
minNum = data[i] > minNum ? minNum : data[i];
maxNum = data[i+1] < maxNum ? maxNum : data[i+1];
}
else {
minNum = data[i + 1] > minNum ? minNum : data[i + 1];
maxNum = data[i] < maxNum ? maxNum : data[i];
}
}
return { minNum, maxNum };
}