From 60813e4b9ac473869cd6ff36e094eb7cf4e21a42 Mon Sep 17 00:00:00 2001
From: Matej Focko <me@mfocko.xyz>
Date: Fri, 29 Nov 2024 21:44:21 +0100
Subject: [PATCH] =?UTF-8?q?go:=20add=20=C2=AB2577.=20Minimum=20Time=20to?=
 =?UTF-8?q?=20Visit=20a=20Cell=20In=20a=20Grid=C2=BB?=
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URL:	https://leetcode.com/problems/minimum-time-to-visit-a-cell-in-a-grid/
Signed-off-by: Matej Focko <me@mfocko.xyz>
---
 go/minimum-time-to-visit-a-cell-in-a-grid.go | 78 ++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 go/minimum-time-to-visit-a-cell-in-a-grid.go

diff --git a/go/minimum-time-to-visit-a-cell-in-a-grid.go b/go/minimum-time-to-visit-a-cell-in-a-grid.go
new file mode 100644
index 0000000..ed031d8
--- /dev/null
+++ b/go/minimum-time-to-visit-a-cell-in-a-grid.go
@@ -0,0 +1,78 @@
+package main
+
+import (
+	"cmp"
+
+	pq "github.com/emirpasic/gods/v2/queues/priorityqueue"
+)
+
+type Position struct {
+	y, x int
+}
+
+func (p *Position) add(v Position) Position {
+	return Position{
+		y: p.y + v.y,
+		x: p.x + v.x,
+	}
+}
+
+type QueueEntry struct {
+	time int
+	pos  Position
+}
+
+func byTime(a, b QueueEntry) int {
+	return cmp.Compare(a.time, b.time)
+}
+
+func minimumTime(grid [][]int) int {
+	if grid[0][1] > 1 && grid[1][0] > 1 {
+		return -1
+	}
+	DIRECTIONS := []Position{
+		Position{1, 0}, Position{-1, 0}, Position{0, 1}, Position{0, -1},
+	}
+
+	rows, cols := len(grid), len(grid[0])
+	visited := make([][]bool, rows)
+	for i, _ := range visited {
+		visited[i] = make([]bool, cols)
+	}
+
+	valid := func(pos Position) bool {
+		return pos.y >= 0 && pos.y < len(visited) &&
+			pos.x >= 0 && pos.x < len(visited[pos.y]) &&
+			!visited[pos.y][pos.x]
+	}
+
+	q := pq.NewWith[QueueEntry](byTime)
+	q.Enqueue(QueueEntry{grid[0][0], Position{0, 0}})
+
+	for current, ok := q.Dequeue(); ok; current, ok = q.Dequeue() {
+		if current.pos.y == rows-1 && current.pos.x == cols-1 {
+			return current.time
+		}
+
+		if visited[current.pos.y][current.pos.x] {
+			continue
+		}
+		visited[current.pos.y][current.pos.x] = true
+
+		for _, dir := range DIRECTIONS {
+			next := current.pos.add(dir)
+			if !valid(next) {
+				continue
+			}
+
+			waiting := 0
+			if (grid[next.y][next.x]-current.time)%2 == 0 {
+				waiting = 1
+			}
+
+			q.Enqueue(QueueEntry{pos: next, time: max(grid[next.y][next.x]+waiting, current.time+1)})
+		}
+	}
+
+	return -1
+}