【模板】st表

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吐個槽，我現線上段樹敲得賊熟練，但是樹狀數組和st表這麼強大的東西竟然基本不會！！！啊啊啊，我太菜了！

代碼：

#include<iostream>#include<cstdio>#include<cmath>#include<ctime>#include<queue>#include<algorithm>#include<cstring>using namespace std;#define duke(i,a,n) for(int i = a;i <= n;i++)#define lv(i,a,n) for(int i = a;i >= n;i--)#define clean(a) memset(a,0,sizeof(a))const int INF = 1 << 30;const int N = 300005;typedef long long ll;typedef double db;template <class T>void read(T &x){    char c;    bool op = 0;    while(c = getchar(), c < ‘0‘ || c > ‘9‘)        if(c == ‘-‘) op = 1;    x = c - ‘0‘;    while(c = getchar(), c >= ‘0‘ && c <= ‘9‘)        x = x * 10 + c - ‘0‘;    if(op) x = -x;}template <class T>void write(T x){    if(x < 0) putchar(‘-‘), x = -x;    if(x >= 10) write(x / 10);    putchar(‘0‘ + x % 10);}int st[1000005][23],a[1000005],n,m;void build(){    duke(i,1,n)    st[i][0] = a[i];    duke(i,1,21)    {        for(int j = 1;j + (1 << i) - 1 <= n;j++)        {            st[j][i] = max(st[j][i - 1],st[j + (1 << (i - 1))][i - 1]);        }    }}void query(int l,int r){    int y = log2(r - l + 1);    int maxn = 0;    maxn = max(st[l][y],st[r - (1 << y) + 1][y]);    printf("%d\n",maxn);}int main(){    read(n);read(m);    duke(i,1,n)        read(a[i]);    build();    while(m--)    {        int l,r;        read(l);read(r);        query(l,r);    }    return 0;}

 

【模板】st表