101.go

// UVa 101 - The Blocks Problem

package main

import (
	"fmt"
	"io"
	"os"
)

var blocks [][]int

func initBlocks(n int) {
	blocks = make([][]int, n)
	for i := range blocks {
		blocks[i] = []int{i}
	}
}

func find(n int) int {
	for i := range blocks {
		for j := range blocks[i] {
			if blocks[i][j] == n {
				return i
			}
		}
	}
	return -1
}

func reset(n int) {
	idx := find(n)
	stack := blocks[idx]
	for stack[len(stack)-1] != n {
		blocks[stack[len(stack)-1]] = append(blocks[stack[len(stack)-1]], stack[len(stack)-1])
		stack = stack[:len(stack)-1]
	}
	blocks[idx] = stack
}

func move(n1, n2 int) {
	pos1, pos2 := find(n1), find(n2)
	blocks[pos1] = blocks[pos1][:len(blocks[pos1])-1]
	blocks[pos2] = append(blocks[pos2], n1)
}

func pile(n1, n2 int) {
	pos1, pos2 := find(n1), find(n2)
	stack := blocks[pos1]
	for i := range stack {
		if stack[i] == n1 {
			blocksToMove := stack[i:]
			blocks[pos1] = stack[:i]
			blocks[pos2] = append(blocks[pos2], blocksToMove...)
			return
		}
	}
}

func process(s1, s2 string, n1, n2 int) {
	if s1 == "move" {
		reset(n1)
	}
	if s2 == "onto" {
		reset(n2)
	}

	switch s1 {
	case "move":
		move(n1, n2)
	case "pile":
		pile(n1, n2)
	}
}

func output(out io.Writer) {
	for i := range blocks {
		fmt.Fprintf(out, "%d:", i)
		for j := range blocks[i] {
			fmt.Fprintf(out, " %d", blocks[i][j])
		}
		fmt.Fprintln(out)
	}
}

func main() {
	in, _ := os.Open("101.in")
	defer in.Close()
	out, _ := os.Create("101.out")
	defer out.Close()

	var n, n1, n2 int
	var s1, s2 string
	fmt.Fscanf(in, "%d", &n)
	initBlocks(n)
	for {
		if fmt.Fscanf(in, "%s", &s1); s1 == "quit" {
			break
		}
		fmt.Fscanf(in, "%d%s%d", &n1, &s2, &n2)
		process(s1, s2, n1, n2)
	}
	output(out)
}