我已经实现了最长公共(public)子序列算法并得到了最长的正确答案,但无法找出打印出最长公共(public)子序列的组成部分的方法。
也就是说,我成功获取了最长公共(public)子序列数组的长度,但我想打印出最长的子序列。
此代码的 Playground 就在这里
http://play.golang.org/p/0sKb_OARnf
/*
X = BDCABA
Y = ABCBDAB => Longest Comman Subsequence is B C B
Dynamic Programming method : O ( n )
*/
package main
import "fmt"
func Max(more ...int) int {
max_num := more[0]
for _, elem := range more {
if max_num < elem {
max_num = elem
}
}
return max_num
}
func Longest(str1, str2 string) int {
len1 := len(str1)
len2 := len(str2)
//in C++,
//int tab[m + 1][n + 1];
//tab := make([][100]int, len1+1)
tab := make([][]int, len1+1)
for i := range tab {
tab[i] = make([]int, len2+1)
}
i, j := 0, 0
for i = 0; i <= len1; i++ {
for j = 0; j <= len2; j++ {
if i == 0 || j == 0 {
tab[i][j] = 0
} else if str1[i-1] == str2[j-1] {
tab[i][j] = tab[i-1][j-1] + 1
if i < len1 {
fmt.Printf("%c", str1[i])
}
} else {
tab[i][j] = Max(tab[i-1][j], tab[i][j-1])
}
}
}
fmt.Println()
return tab[len1][len2]
}
func main() {
str1 := "AGGTABTABTABTAB"
str2 := "GXTXAYBTABTABTAB"
fmt.Println(Longest(str1, str2))
//Actual Longest Common Subsequence: GTABTABTABTAB
//GGGGGTAAAABBBBTTTTAAAABBBBTTTTAAAABBBBTTTTAAAABBBB
//13
str3 := "AGGTABGHSRCBYJSVDWFVDVSBCBVDWFDWVV"
str4 := "GXTXAYBRGDVCBDVCCXVXCWQRVCBDJXCVQSQQ"
fmt.Println(Longest(str3, str4))
//Actual Longest Common Subsequence: ?
//GGGTTABGGGHHRCCBBBBBBYYYJSVDDDDDWWWFDDDDDVVVSSSSSBCCCBBBBBBVVVDDDDDWWWFWWWVVVVVV
//14
}
当我尝试在选项卡更新时打印出子序列时,结果是重复的。 我想为 str1 和 str2 打印出类似“GTABTABTABTAB”的内容
提前致谢。
最佳答案
编辑:看来我是仓促回答了这个问题。在维基百科页面上 Longest Common Subsequnce一旦计算出 LCS,他们就会给出打印出 LCS 的伪代码。我会在有空的时候尽快在 go up 中添加一个实现。
旧的无效答案
一旦您将某个角色注册为子序列的一部分,您就会忘记从该角色继续前进。
下面的代码应该可以工作。查看 fmt.Printf("%c", srt1[i])
行之后的两行。
/*
X = BDCABA
Y = ABCBDAB => Longest Comman Subsequence is B C B
Dynamic Programming method : O ( n )
*/
package main
import "fmt"
func Max(more ...int) int {
max_num := more[0]
for _, elem := range more {
if max_num < elem {
max_num = elem
}
}
return max_num
}
func Longest(str1, str2 string) int {
len1 := len(str1)
len2 := len(str2)
//in C++,
//int tab[m + 1][n + 1];
//tab := make([][100]int, len1+1)
tab := make([][]int, len1+1)
for i := range tab {
tab[i] = make([]int, len2+1)
}
i, j := 0, 0
for i = 0; i <= len1; i++ {
for j = 0; j <= len2; j++ {
if i == 0 || j == 0 {
tab[i][j] = 0
} else if str1[i-1] == str2[j-1] {
tab[i][j] = tab[i-1][j-1] + 1
if i < len1 {
fmt.Printf("%c", str1[i])
//Move on the the next character in both sequences
i++
j++
}
} else {
tab[i][j] = Max(tab[i-1][j], tab[i][j-1])
}
}
}
fmt.Println()
return tab[len1][len2]
}
func main() {
str1 := "AGGTABTABTABTAB"
str2 := "GXTXAYBTABTABTAB"
fmt.Println(Longest(str1, str2))
//Actual Longest Common Subsequence: GTABTABTABTAB
//GGGGGTAAAABBBBTTTTAAAABBBBTTTTAAAABBBBTTTTAAAABBBB
//13
str3 := "AGGTABGHSRCBYJSVDWFVDVSBCBVDWFDWVV"
str4 := "GXTXAYBRGDVCBDVCCXVXCWQRVCBDJXCVQSQQ"
fmt.Println(Longest(str3, str4))
//Actual Longest Common Subsequence: ?
//GGGTTABGGGHHRCCBBBBBBYYYJSVDDDDDWWWFDDDDDVVVSSSSSBCCCBBBBBBVVVDDDDDWWWFWWWVVVVVV
//14
}
关于algorithm - 转到 : longest common subsequence to print result array,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/20145795/