HihoCoder - 1068（RMQ问题ST表，模板）

题意：

很基础的模板题，但是要封装一个告诉的St表模板类出来，实测效率不低。

代码：

// 决定写一个ST表的类，维护区间最小值
#include <iostream>
#include <vector>
#include <stdio.h>
using namespace std;
template <class Type>
class StList
{
private:
	bool is_init;
	int st_size;
	vector <Type> v;
	vector <int> log2_floor; // log2_floor[x]表示：(1<<log2_floor[x]) <= x 的最大整数值 log2_floor[x]
	vector < vector<Type> > st; // st[i][j]: min[ v[i] ... v[i+(1<<j)] ) // len = 1<<j
	void getStSize();
	Type min(const Type& l, const Type& r);

public:
	StList();
	~StList();
	void init();
	int size();
	void push_back(Type x);
	Type getMin(int l, int r);
};
template <class Type>
void StList<Type>::getStSize() {
	st_size = 0;
	while ((1 << st_size) < v.size()) {
		st_size++;
	}
}
template <class Type>
Type StList<Type>::min(const Type& l, const Type& r) {
	return l < r ? l : r;
}
template <class Type> 
StList<Type>::StList() {
	is_init = true;	st_size = 0;
	v.clear();	st.clear();	log2_floor.clear();
}
template <class Type>
StList<Type>::~StList() {
	v.clear();	st.clear();	log2_floor.clear();
}
template <class Type>
void StList<Type>::init() {
	getStSize();
	st.clear();
	vector <Type> unit(st_size + 1);
	for (int i = 0; i < size(); i++) { // init st[i][0]
		st.push_back(unit);
		log2_floor.push_back(-1);
;		st[i][0] = v[i];
	}
	for (int i = 1; i < size(); i++) { // init log2_floor;
		log2_floor[i] = log2_floor[i / 2] + 1;
	}
	for (int j = 1; j <= st_size; j++){
		for (int i = 0; i < st.size(); i++) {
			if (i + (1 << (j - 1)) >= st.size()) {
				break;
			}
			st[i][j] = min(st[i][j - 1], st[i + (1 << (j - 1))][j - 1]);
		}
	}
	is_init = true;
}
template <class Type>
int StList<Type>::size() {
	return v.size();
}
template <class Type>
void StList<Type>::push_back(Type x) {
	is_init = false;
	v.push_back(x);
}
template <class Type>
Type StList<Type>::getMin(int l, int r) {
	if (is_init == false) {
		init();
	}
	if (l > r || l < 0 || r >= v.size()) {
		return Type();
	}
	int len = (r - l + 1);
	int mov = log2_floor[len];
	return min(st[l][mov], st[r - (1 << mov) + 1][mov]);
}
int main()
{
	StList<int> ans;
	int n, m;
	while (cin >> n) {
		for (int i = 0; i < n; i++) {
			int temp;
			scanf("%d", &temp);
			ans.push_back(temp);
		}
		cin >> m;
		while (m--) {
			int l, r;
			scanf("%d%d", &l, &r);
			printf("%d\n", ans.getMin(l - 1, r - 1));
		}
	}
}