尝试将切片作为参数传递给递归函数 (Go) 时，切片超出范围

Question

我正在尝试将切片作为参数传递给递归函数。由于切片作为参考传递，我相信我传递给它的递归函数应该能够毫无问题地执行操作。我只使用 append() ，因此不应该对容量不足的切片有问题吗？package mainimport "fmt"func allPossiblePaths(arrGraph [8][8]bool, src int, dest int) [][]int {    var visited []bool //a slice that marks if visited    var path []int     //a slice to store a possible path    var paths [][]int  //a slice to store all paths    visited = make([]bool, 8) //set all nodes to unvisited    dfs(arrGraph, src, dest, visited, path, paths)    return paths}func dfs(myGraph [8][8]bool, src int, dest int, visited []bool, path []int, paths [][]int) {    //add current node to path    path = append(path, src)    //mark current node as visited    visited[src] = true    //if the current node is the destination    //print the path and return    if src == dest {        //make a copy of path slice        buffer := make([]int, len(path))        copy(buffer, path)        //append the copy of path slice into the slice of paths        paths = append(paths, buffer)        fmt.Println(path) //Just for debugging purpose        return    }    for i := 1; i <= 7; i++ { //loop through all nodes        //if ith node is a neighbour of the current node and it is not visited        if myGraph[src][i] && visited[i] == false {            // call dfs on the current node            dfs(myGraph, i, dest, visited, path, paths)            //mark the current node as unvisited            //so that we can other paths to the final destination            visited[i] = false            //re-slice the slice - get rid of the current node            path = path[:len(path)-1]        }    }}预期输出：（在使用全局变量而不是将变量传递给函数时实现）[[1 2 3 4 6 7] [1 2 3 6 7] [1 2 5 6 7] [1 3 2 5 6 7] [1 3 4 6 7] [1 3 6 7] [1 6 7]]知道我做错了什么吗？

Answer 1

错误消息准确地说明了问题所在：

恐慌：运行时错误：切片超出范围

由于您正在迭代调用相同的函数并重新切片切片，因此您每次都需要检查是否达到切片容量范围，换句话说，如果切片指针指向有效地址（索引），否则您会收到out of range error消息.

而且由于您正在进行递归迭代，因此每次通过减小路径长度，您必须检查切片索引是否在有效范围内。

//re-slice the slice - get rid of the current node

if len(path) > 0 {

       path = path[:len(path)-1]

}

https://play.golang.org/p/pX2TlAP-bp

Answer 2

我通过使用指向我的切片“路径”的指针作为递归函数的参数来解决它。现在可以了！不管怎么说，还是要谢谢你。

package main

import "fmt"

func allPossiblePaths(arrGraph [8][8]bool, src int, dest int) [][]int {

    var visited []bool //a slice that marks if visited

    var path []int     //a slice to store a possible path

    var paths [][]int  //a slice to store all paths

    visited = make([]bool, 8) //set all nodes to unvisited

    dfs(arrGraph, src, dest, visited, &path, paths)

    return paths

}

func dfs(myGraph [8][8]bool, src int, dest int, visited []bool, path *[]int, paths [][]int) {

    //add current node to path

    *path = append(*path, src)

    //mark current node as visited

    visited[src] = true

    //if the current node is the destination

    //print the path and return

    if src == dest {

        //make a copy of path slice

        buffer := make([]int, len(*path))

        copy(buffer, *path)

        //append the copy of path slice into the slice of paths

        paths = append(paths, buffer)

        fmt.Println(*path) //Just for debugging purpose

        return

    }

    for i := 1; i <= 7; i++ { //loop through all nodes

        //if ith node is a neighbour of the current node and it is not visited

        if myGraph[src][i] && visited[i] == false {

            // call dfs on the current node

            dfs(myGraph, i, dest, visited, path, paths)

            //mark the current node as unvisited

            //so that we can other paths to the final destination

            visited[i] = false

            //re-slice the slice - get rid of the current node

            *path = (*path)[:len(*path)-1]

            //fmt.Println(path)

        }

    }

}

func main() {

    var myGraph [8][8]bool //the graph

    //creating the graph

    myGraph[1] = [...]bool{false, false, true, true, false, false, true, false}

    myGraph[2] = [...]bool{false, true, false, true, false, true, false, false}

    myGraph[3] = [...]bool{false, true, true, false, true, false, true, false}

    myGraph[4] = [...]bool{false, false, false, true, false, false, true, false}

    myGraph[5] = [...]bool{false, false, true, false, false, false, true, false}

    myGraph[6] = [...]bool{false, true, false, true, true, false, false, true}

    myGraph[7] = [...]bool{false, false, false, false, false, false, true, false}

    fmt.Println(allPossiblePaths(myGraph, 1, 7))

}