用c++写出线段树的模板代码

好的，以下是线段树的模板代码：

#include <stdio.h>
#define MAXN 100005

int n, m;
int a[MAXN];
int tree[MAXN << 2];

void build(int node, int left, int right) {
    if (left == right) {
        tree[node] = a[left];
        return;
    }
    int mid = (left + right) >> 1;
    build(node << 1, left, mid);
    build(node << 1 | 1, mid + 1, right);
    tree[node] = tree[node << 1] + tree[node << 1 | 1];
}

void update(int node, int left, int right, int pos, int val) {
    if (left == right) {
        tree[node] = val;
        return;
    }
    int mid = (left + right) >> 1;
    if (pos <= mid) update(node << 1, left, mid, pos, val);
    else update(node << 1 | 1, mid + 1, right, pos, val);
    tree[node] = tree[node << 1] + tree[node << 1 | 1];
}

int query(int node, int left, int right, int l, int r) {
    if (left >= l && right <= r) return tree[node];
    int mid = (left + right) >> 1, res = ;
    if (l <= mid) res += query(node << 1, left, mid, l, r);
    if (r > mid) res += query(node << 1 | 1, mid + 1, right, l, r);
    return res;
}

int main() {
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; ++i) scanf("%d", &a[i]);
    build(1, 1, n);
    while (m--) {
        int op, x, y;
        scanf("%d%d%d", &op, &x, &y);
        if (op == 1) update(1, 1, n, x, y);
        else printf("%d\n", query(1, 1, n, x, y));
    }
    return ;
}

希望能够帮到你！