leetcode【Palindrome Partitioning 回文字符串划分】

描述

Palindrome Partitioning Feb 284465 / 15553

Given a string s, partition s such that every substring of the partition is a palindrome.

Return all possible palindrome partitioning of s.

For example, given s =

"aab"

,

Return

[
["aa","b"],
["a","a","b"]
]

字符串能否划分成多个回文串？如果能，输出所有的划分方法。

分析

用递归来做，任意一个划分的方法，都是一个vector<string>，如果它非空，那么肯定存在他的第一个元素。对任意一个字符串s：

for i=1:s.length

s1=s[0~i]

s2=[i~end]

s1是回文串吗？如果不是，那就continue

如果是：

对s2进行递归，得到s2的输出，s2可能有多种划分方式，那么，在每一种的前面加上s1即可！

end

递归结束的条件是，输入的字符串长度为0（那么直接返回空的vector），或者输入的字符串的长度为1（返回仅包含该字母的veector）。

代码

class Solution {
public:
bool is_huiwen(const string &s)
{
int l=s.length();
int i;
for(i=0; i<l/2; i++)
if(s[i] != s[l-1-i])
return false;
return true;
}

vector<vector<string> > partition(string s)
{

int l=s.length();
//   cout<<"l="<<l<<endl;
vector<vector<string> >vv;
vector<string> v;
if(l==0)
{
return vv;
}

int i;
for(i=1; i<l; i++)
{
string ts=s.substr(0,i);
//   cout<<"i= "<<i<<" ts= "<<ts;
if(! is_huiwen(ts) )
continue;
string ts_end=s.substr(i,s.length() - i);
//    cout<<"ts_end = "<<ts_end<<endl;
vector<vector<string> > vvt;
vvt=partition(ts_end);
int j;
for(j=0; j<vvt.size(); j++)
{

vvt[j].insert(vvt[j].begin(), ts);
//  for(int m=0;m<vvt[j].size();m++)cout<<vvt[j][m]<<" ";cout<<endl;
vv.push_back(vvt[j]);
}
}
if(is_huiwen(s) )
{
v.push_back(s);
vv.push_back(v);
}
return vv;
}
};

Run Status: Accepted!

Program Runtime: 12 milli secs

Progress: 10/10 test cases passed.

input
output
expected
"a"
[["a"]]
[["a"]]
"ab"
[["a","b"]]
[["a","b"]]
"bb"
[["b","b"],["bb"]]
[["b","b"],["bb"]]
"cdd"
[["c","d","d"],["c","dd"]]
[["c","d","d"],["c","dd"]]
"dde"
[["d","d","e"],["dd","e"]]
[["d","d","e"],["dd","e"]]
"efe"
[["e","f","e"],["efe"]]
[["e","f","e"],["efe"]]
"fff"
[["f","f","f"],["f","ff"],["ff","f"],["fff"]]
[["f","f","f"],["f","ff"],["ff","f"],["fff"]]
"abbab"
[["a","b","b","a","b"],["a","b","bab"],["a","bb","a","b"],["abba","b"]]
[["a","b","b","a","b"],["a","b","bab"],["a","bb","a","b"],["abba","b"]]
"leet"
[["l","e","e","t"],["l","ee","t"]]
[["l","e","e","t"],["l","ee","t"]]
"coder"
[["c","o","d","e","r"]]
[["c","o","d","e","r"]]

Run Status: Accepted!

Program Runtime: 368 milli secs

Progress: 20/20 test cases passed.

input
output
expected
"a"
[["a"]]
[["a"]]
"ab"
[["a","b"]]
[["a","b"]]
"bb"
[["b","b"],["bb"]]
[["b","b"],["bb"]]
"cdd"
[["c","d","d"],["c","dd"]]
[["c","d","d"],["c","dd"]]
"dde"
[["d","d","e"],["dd","e"]]
[["d","d","e"],["dd","e"]]
"efe"
[["e","f","e"],["efe"]]
[["e","f","e"],["efe"]]
"fff"
[["f","f","f"],["f","ff"],["ff","f"],["fff"]]
[["f","f","f"],["f","ff"],["ff","f"],["fff"]]
"abbab"
[["a","b","b","a","b"],["a","b","bab"],["a","bb","a","b"],["abba","b"]]
[["a","b","b","a","b"],["a","b","bab"],["a","bb","a","b"],["abba","b"]]
"leet"
[["l","e","e","t"],["l","ee","t"]]
[["l","e","e","t"],["l","ee","t"]]
"coder"
[["c","o","d","e","r"]]
[["c","o","d","e","r"]]
"cbbbcc"
[["c","b","b","b","c","c"],["c","b","b","b","cc"],["c","b","bb","c","c"],["c","b","bb","cc"],["c","bb","b","c","c"],["c","bb","b","cc"],["c","bbb","c","c"],["c","bbb","cc"],["cbbbc","c"]]
[["c","b","b","b","c","c"],["c","b","b","b","cc"],["c","b","bb","c","c"],["c","b","bb","cc"],["c","bb","b","c","c"],["c","bb","b","cc"],["c","bbb","c","c"],["c","bbb","cc"],["cbbbc","c"]]
"ccaacabacb"
[["c","c","a","a","c","a","b","a","c","b"],["c","c","a","a","c","aba","c","b"],["c","c","a","a","cabac","b"],["c","c","a","aca","b","a","c","b"],["c","c","aa","c","a","b","a","c","b"],["c","c","aa","c","aba","c","b"],["c","c","aa","cabac","b"],["c","caac","a","b","a","c","b"],["c","caac","aba","c","b"],["cc","a","a","c","a","b","a","c","b"],["cc","a","a","c","aba","c","b"],["cc","a","a","cabac","b"],["cc","a","aca","b","a","c","b"],["cc","aa","c","a","b","a","c","b"],["cc","aa","c","aba","c","b"],["cc","aa","cabac","b"]]
[["c","c","a","a","c","a","b","a","c","b"],["c","c","a","a","c","aba","c","b"],["c","c","a","a","cabac","b"],["c","c","a","aca","b","a","c","b"],["c","c","aa","c","a","b","a","c","b"],["c","c","aa","c","aba","c","b"],["c","c","aa","cabac","b"],["c","caac","a","b","a","c","b"],["c","caac","aba","c","b"],["cc","a","a","c","a","b","a","c","b"],["cc","a","a","c","aba","c","b"],["cc","a","a","cabac","b"],["cc","a","aca","b","a","c","b"],["cc","aa","c","a","b","a","c","b"],["cc","aa","c","aba","c","b"],["cc","aa","cabac","b"]]
"racecar"
[["r","a","c","e","c","a","r"],["r","a","cec","a","r"],["r","aceca","r"],["racecar"]]
[["r","a","c","e","c","a","r"],["r","a","cec","a","r"],["r","aceca","r"],["racecar"]]
"danaranad"
[["d","a","n","a","r","a","n","a","d"],["d","a","n","a","r","ana","d"],["d","a","n","ara","n","a","d"],["d","a","naran","a","d"],["d","ana","r","a","n","a","d"],["d","ana","r","ana","d"],["d","anarana","d"],["danaranad"]]
[["d","a","n","a","r","a","n","a","d"],["d","a","n","a","r","ana","d"],["d","a","n","ara","n","a","d"],["d","a","naran","a","d"],["d","ana","r","a","n","a","d"],["d","ana","r","ana","d"],["d","anarana","d"],["danaranad"]]

自己写的测试代码：

#include <iostream>
#include <vector>
#include <string>
using namespace std;
vector<vector<string> > partition(string s) ;
int main()
{
string ss("ccaacabacb");
vector<vector<string> > vv = partition(ss);
int i,j;
for(i=0; i<vv.size(); i++)
{
for(j=0; j<vv[i].size(); j++)
{
cout<<vv[i][j]<<" ";
}
cout<<endl;
}

return 0;
}

bool is_huiwen(const string &s)
{
int l=s.length();
int i;
for(i=0; i<l/2; i++)
if(s[i] != s[l-1-i])
return false;
return true;
}

vector<vector<string> > partition(string s)
{

int l=s.length();
//   cout<<"l="<<l<<endl;
vector<vector<string> >vv;
vector<string> v;
if(l==0)
{
return vv;
}

int i;
for(i=1; i<l; i++)
{
string ts=s.substr(0,i);
//   cout<<"i= "<<i<<" ts= "<<ts;
if(! is_huiwen(ts) )
continue;
string ts_end=s.substr(i,s.length() - i);
//    cout<<"ts_end = "<<ts_end<<endl;
vector<vector<string> > vvt;
vvt=partition(ts_end);
int j;
for(j=0; j<vvt.size(); j++)
{

vvt[j].insert(vvt[j].begin(), ts);
//  for(int m=0;m<vvt[j].size();m++)cout<<vvt[j][m]<<" ";cout<<endl;
vv.push_back(vvt[j]);
}
}
if(is_huiwen(s) )
{
v.push_back(s);
vv.push_back(v);
}
return vv;
}

运行：

chen@chen-book1:~$ ./cpp

c c a a c a b a c b

c c a a c aba c b

c c a a cabac b

c c a aca b a c b

c c aa c a b a c b

c c aa c aba c b

c c aa cabac b

c caac a b a c b

c caac aba c b

cc a a c a b a c b

cc a a c aba c b

cc a a cabac b

cc a aca b a c b

cc aa c a b a c b

cc aa c aba c b

cc aa cabac b