acwing-246. 区间最大公约数(线段树+gcd)[通俗易懂]

输入样例：
5 5
1 3 5 7 9
Q 1 5
C 1 5 1
Q 1 5
C 3 3 6
Q 2 4
输出样例：
1
2
4

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 5e5 + 10;
#define lson u << 1
#define rson u << 1 | 1
struct Node{ 
   
    int l,r;
    ll gcd,sum;
}trie[N * 4];
ll a[N],d[N];
int gcd(int a,int b){ 
   
    return b == 0 ? a : gcd(b, a % b);
}
void pushup(int u){ 
   
    trie[u].sum = trie[lson].sum + trie[rson].sum;
    trie[u].gcd = gcd(trie[lson].gcd,trie[rson].gcd);
}
void build(int u,int l,int r){ 
   
    if(l == r)trie[u] = { 
   l,r,d[l],d[l]};
    else{ 
   
        trie[u] = { 
   l,r};
        int mid = (l + r) >> 1;
        build(lson,l,mid);
        build(rson,mid + 1,r);
        pushup(u);
    }
}
void modify(int u,int x,ll y){ 
   
    if(trie[u].l == x && trie[u].r == x)trie[u].sum += y,trie[u].gcd += y;
    else{ 
   
        int mid = (trie[u].l + trie[u].r) >> 1;
        if(x <= mid)modify(lson,x,y);
        else modify(rson,x,y);
        pushup(u);
    }
}
Node query(int u,int l,int r){ 
   
    if(trie[u].l >= l && trie[u].r <= r){ 
   
        Node t;
        t.sum = trie[u].sum;
        t.gcd = trie[u].gcd;
    
        return t;
    }
    int mid = (trie[u].l + trie[u].r) >> 1;
    if(r <= mid)return query(lson,l,r);
    else if(l > mid)return query(rson,l,r);
    else{ 
   
        auto left = query(lson,l,r),right = query(rson,l,r);
        Node t;
        t.sum = left.sum + right.sum;
        t.gcd = gcd(left.gcd,right.gcd);
        return t;
    }
}

int main(){ 
   
    int n,m;
    cin>>n>>m;
    ios::sync_with_stdio(false);
    for(int i = 1;i <= n;i ++){ 
   
        cin>>a[i];
        d[i] = a[i] - a[i - 1];
    }
    build(1,1,n + 1);
    char t;
    ll x,y,dd;
    for(int i = 0;i < m;i ++){ 
   
        cin>>t>>x>>y;
        if(t == 'C')cin>>dd;
        if(x > y)swap(x,y);
        if(t == 'C'){ 
   
            modify(1,x,dd);
            modify(1,y + 1,-dd);
        }
        else{ 
   
            auto left = query(1,1,x),right = query(1,x + 1,y);
            cout<<gcd(left.sum,right.gcd)<<endl;
        }
    }
    return 0;
}