Solution.go

func modifiedGraphEdges(n int, edges [][]int, source int, destination int, target int) [][]int {
	const inf int = 2e9
	dijkstra := func(edges [][]int) int {
		g := make([][]int, n)
		dist := make([]int, n)
		vis := make([]bool, n)
		for i := range g {
			g[i] = make([]int, n)
			for j := range g[i] {
				g[i][j] = inf
			}
			dist[i] = inf
		}
		dist[source] = 0
		for _, e := range edges {
			a, b, w := e[0], e[1], e[2]
			if w == -1 {
				continue
			}
			g[a][b], g[b][a] = w, w
		}
		for i := 0; i < n; i++ {
			k := -1
			for j := 0; j < n; j++ {
				if !vis[j] && (k == -1 || dist[j] < dist[k]) {
					k = j
				}
			}
			vis[k] = true
			for j := 0; j < n; j++ {
				dist[j] = min(dist[j], dist[k]+g[k][j])
			}
		}
		return dist[destination]
	}
	d := dijkstra(edges)
	if d < target {
		return [][]int{}
	}
	ok := d == target
	for _, e := range edges {
		if e[2] > 0 {
			continue
		}
		if ok {
			e[2] = inf
			continue
		}
		e[2] = 1
		d := dijkstra(edges)
		if d <= target {
			ok = true
			e[2] += target - d
		}
	}
	if ok {
		return edges
	}
	return [][]int{}
}

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