For problem statement at 0-999/800-899/830-839/838/problemB.txt this is a correct solution, but verifier at 0-999/800-899/830-839/838/verifierB.go ends with All tests passed can you fix the verifier? package main

import (
	"io"
	"os"
	"strconv"
)

type Edge struct {
	to int
	id int
	w  int64
}

type Fenwick struct {
	tree []int64
}

func (f *Fenwick) Add(idx int, val int64) {
	for ; idx < len(f.tree); idx += idx & -idx {
		f.tree[idx] += val
	}
}

func (f *Fenwick) RangeAdd(L, R int, val int64) {
	f.Add(L, val)
	f.Add(R+1, -val)
}

func (f *Fenwick) Query(idx int) int64 {
	var sum int64
	for ; idx > 0; idx -= idx & -idx {
		sum += f.tree[idx]
	}
	return sum
}

func min(a, b int64) int64 {
	if a < b {
		return a
	}
	return b
}

func main() {
	input, _ := io.ReadAll(os.Stdin)
	pos := 0
	nextInt := func() int {
		for pos < len(input) && input[pos] <= ' ' {
			pos++
		}
		if pos >= len(input) {
			return 0
		}
		res := 0
		for pos < len(input) && input[pos] > ' ' {
			res = res*10 + int(input[pos]-'0')
			pos++
		}
		return res
	}
	nextInt64 := func() int64 {
		for pos < len(input) && input[pos] <= ' ' {
			pos++
		}
		if pos >= len(input) {
			return 0
		}
		var res int64 = 0
		for pos < len(input) && input[pos] > ' ' {
			res = res*10 + int64(input[pos]-'0')
			pos++
		}
		return res
	}

	n := nextInt()
	if n == 0 {
		return
	}
	q := nextInt()

	adj := make([][]Edge, n+1)
	upEdgeChild := make([]int, 2*n)
	backEdgeNode := make([]int, 2*n)
	weight := make([]int64, 2*n)

	for i := 1; i <= n-1; i++ {
		u := nextInt()
		v := nextInt()
		w := nextInt64()
		adj[u] = append(adj[u], Edge{v, i, w})
		weight[i] = w
	}

	for i := n; i <= 2*n-2; i++ {
		u := nextInt()
		_ = nextInt()
		w := nextInt64()
		backEdgeNode[i] = u
		weight[i] = w
	}

	timer := 0
	in := make([]int, n+1)
	out := make([]int, n+1)
	d := make([]int64, n+1)

	var dfs func(int)
	dfs = func(u int) {
		timer++
		in[u] = timer
		for _, edge := range adj[u] {
			v := edge.to
			upEdgeChild[edge.id] = v
			d[v] = d[u] + edge.w
			dfs(v)
		}
		out[u] = timer
	}
	dfs(1)

	backWeight := make([]int64, n+1)
	for i := n; i <= 2*n-2; i++ {
		u := backEdgeNode[i]
		backWeight[u] = weight[i]
	}

	leaf := make([]int64, n+1)
	leaf[1] = 1e18
	for i := 2; i <= n; i++ {
		leaf[in[i]] = d[i] + backWeight[i]
	}

	fenwick := &Fenwick{tree: make([]int64, n+2)}
	for i := 1; i <= n; i++ {
		fenwick.RangeAdd(in[i], in[i], d[i])
	}

	minVal := make([]int64, 4*n+1)
	lazy := make([]int64, 4*n+1)

	var build func(int, int, int)
	build = func(node, l, r int) {
		if l == r {
			minVal[node] = leaf[l]
			return
		}
		mid := (l + r) / 2
		build(node*2, l, mid)
		build(node*2+1, mid+1, r)
		minVal[node] = min(minVal[node*2], minVal[node*2+1])
	}
	build(1, 1, n)

	var pushDown func(int)
	pushDown = func(node int) {
		if lazy[node] != 0 {
			lazy[node*2] += lazy[node]
			minVal[node*2] += lazy[node]
			lazy[node*2+1] += lazy[node]
			minVal[node*2+1] += lazy[node]
			lazy[node] = 0
		}
	}

	var update func(int, int, int, int, int, int64)
	update = func(node, l, r, ql, qr int, val int64) {
		if ql <= l && r <= qr {
			minVal[node] += val
			lazy[node] += val
			return
		}
		pushDown(node)
		mid := (l + r) / 2
		if ql <= mid {
			update(node*2, l, mid, ql, qr, val)
		}
		if qr > mid {
			update(node*2+1, mid+1, r, ql, qr, val)
		}
		minVal[node] = min(minVal[node*2], minVal[node*2+1])
	}

	var query func(int, int, int, int, int) int64
	query = func(node, l, r, ql, qr int) int64 {
		if ql <= l && r <= qr {
			return minVal[node]
		}
		pushDown(node)
		mid := (l + r) / 2
		res := int64(2e18)
		if ql <= mid {
			res = min(res, query(node*2, l, mid, ql, qr))
		}
		if qr > mid {
			res = min(res, query(node*2+1, mid+1, r, ql, qr))
		}
		return res
	}

	var output []byte
	for i := 0; i < q; i++ {
		typ := nextInt()
		if typ == 1 {
			idx := nextInt()
			w := nextInt64()
			delta := w - weight[idx]
			weight[idx] = w
			if idx <= n-1 {
				c := upEdgeChild[idx]
				fenwick.RangeAdd(in[c], out[c], delta)
				update(1, 1, n, in[c], out[c], delta)
			} else {
				u := backEdgeNode[idx]
				update(1, 1, n, in[u], in[u], delta)
			}
		} else {
			u := nextInt()
			v := nextInt()
			if in[u] <= in[v] && in[v] <= out[u] {
				ans := fenwick.Query(in[v]) - fenwick.Query(in[u])
				output = strconv.AppendInt(output, ans, 10)
				output = append(output, '\n')
			} else {
				du := fenwick.Query(in[u])
				dv := fenwick.Query(in[v])
				mu := query(1, 1, n, in[u], out[u])
				ans := mu - du + dv
				output = strconv.AppendInt(output, ans, 10)
				output = append(output, '\n')
			}
		}
	}
	os.Stdout.Write(output)
}