感觉大佬的算法教程。
我在学习单调栈的时候，发现1.4板子题-1.4.2代码实现有错误。运行结果和样例的结果不一致
void sumSubarrayMins(vector &A) {
int n = A.size();
vector lmin(n, -1);
vector rmin(n, -1);
stack stk; // 单调递增栈
for (int i = 0; i < A.size(); i++) {
while (stk.size() && A[i] <= A[stk.top()]) {
rmin[stk.top()] = A[i];
stk.pop();
if (stk.size()) lmin[i] = A[stk.top()];
}
stk.push(i);
}
}

此处的if (stk.size()) lmin[i] = A[stk.top()];应该放在while循环外面，即

void sumSubarrayMins(vector &A) {
int n = A.size();
vector lmin(n, -1);
vector rmin(n, -1);
stack stk; // 单调递增栈
for (int i = 0; i < A.size(); i++) {
while (stk.size() && A[i] <= A[stk.top()]) {
rmin[stk.top()] = A[i];
stk.pop();
}
if (stk.size()) lmin[i] = A[stk.top()];
stk.push(i);
}
}

https://muyids.github.io/simple-algorithm/
https://muyids.github.io/simple-algorithm/
这两个都打不开