func_code_string: #include <bits/stdc++.h>   using namespace std;   const int mod = 1e9;   int n, m;   long long a[200100], fibo[200100], sumfibo[200100];   struct Segment_Tree {     int left, right, len;     long long s0, s1;   } tree[200100 << 2];   struct Data {     long long a[2][2];   } bb[200100], one, b;   Data operator*(const Data x, const Data y) {     Data res;     res.a[0][0] =         (x.a[0][0] * y.a[0][0] % mod + x.a[0][1] * y.a[1][0] % mod) % mod;     res.a[0][1] =         (x.a[0][0] * y.a[0][1] % mod + x.a[0][1] * y.a[1][1] % mod) % mod;     res.a[1][0] =         (x.a[1][0] * y.a[0][0] % mod + x.a[1][1] * y.a[1][0] % mod) % mod;     res.a[1][1] =         (x.a[1][0] * y.a[0][1] % mod + x.a[1][1] * y.a[1][1] % mod) % mod;     return res;   }   long long cal_fx(long long s0, long long s1, int l) {     long long res;     res = (bb[l - 1].a[0][0] * s1 % mod + bb[l - 1].a[0][1] * s0 % mod) % mod;     return res;   }   void plant_tree(int id, int l, int r) {     tree[id].left = l, tree[id].right = r;     tree[id].len = r - l + 1;     if (l == r) {       tree[id].s0 = fibo[0] * a[l] % mod;       tree[id].s1 = fibo[1] * a[l] % mod;       return;     }     int mid = (l + r) >> 1;     plant_tree(id << 1, l, mid);     plant_tree(id << 1 | 1, mid + 1, r);     tree[id].s0 =         (tree[id << 1].s0 +          cal_fx(tree[id << 1 | 1].s0, tree[id << 1 | 1].s1, tree[id << 1].len)) %         mod;     tree[id].s1 =         (tree[id << 1].s1 + cal_fx(tree[id << 1 | 1].s0, tree[id << 1 | 1].s1,                                    tree[id << 1].len + 1)) %         mod;   }   void push_down() {}   void update_pos(int id, int pos, long long val) {     if (tree[id].left == tree[id].right) {       tree[id].s0 = fibo[0] * val % mod;       tree[id].s1 = fibo[1] * val % mod;       return;     }     int mid = (tree[id].left + tree[id].right) >> 1;     if (pos <= mid)       update_pos(id << 1, pos, val);     else       update_pos(id << 1 | 1, pos, val);     tree[id].s0 =         (tree[id << 1].s0 +          cal_fx(tree[id << 1 | 1].s0, tree[id << 1 | 1].s1, tree[id << 1].len)) %         mod;     tree[id].s1 =         (tree[id << 1].s1 + cal_fx(tree[id << 1 | 1].s0, tree[id << 1 | 1].s1,                                    tree[id << 1].len + 1)) %         mod;   }   Segment_Tree query(int id, int l, int r) {     if (tree[id].left == l && tree[id].right == r) {       return tree[id];     }     int mid = (tree[id].left + tree[id].right) >> 1;     if (r <= mid)       return query(id << 1, l, r);     else if (mid < l)       return query(id << 1 | 1, l, r);     else {       Segment_Tree leftson, rightson, now;       leftson = query(id << 1, l, mid);       rightson = query(id << 1 | 1, mid + 1, r);       now.s0 = (leftson.s0 + cal_fx(rightson.s0, rightson.s1, leftson.len)) % mod;       now.s1 =           (leftson.s1 + cal_fx(rightson.s0, rightson.s1, leftson.len + 1)) % mod;       now.len = leftson.len + rightson.len;       return now;     }   }   int main() {     fibo[0] = fibo[1] = 1;     for (int i = 2; i < 200100; i++) {       fibo[i] = (fibo[i - 2] + fibo[i - 1]) % mod;     }     sumfibo[0] = fibo[0];     for (int i = 1; i < 200100; i++) {       sumfibo[i] = (sumfibo[i - 1] + fibo[i]) % mod;     }     one.a[0][0] = one.a[1][1] = 1;     one.a[1][0] = one.a[0][1] = 0;     b.a[0][0] = b.a[0][1] = b.a[1][0] = 1;     b.a[1][1] = 0;     bb[0] = one;     for (int i = 1; i < 200100; i++) {       bb[i] = bb[i - 1] * b;     }     scanf( %d %d , &n, &m);     for (int i = 1; i <= n; i++) {       scanf( %lld , a + i);     }     plant_tree(1, 1, n);     while (m--) {       int type;       scanf( %d , &type);       if (type == 1) {         int x, v;         scanf( %d %d , &x, &v);         update_pos(1, x, v);       } else if (type == 2) {         int l, r;         scanf( %d %d , &l, &r);         Segment_Tree res = query(1, l, r);         printf( %lld n , res.s0);       } else if (type == 3) {         int l, r, d;         scanf( %d %d %d , &l, &r, &d);       }     }   }   