今天在csdn上无意看到这个题目，突然很有兴趣。因为我觉得这个看似简单的问题似乎也没那和简单。看到别人写个的几个，可是我感觉都不太合理，于是决定自己动手写。所谓连续的数字串应该做何理解，我觉得像12345，54321这样的都是算的，又如123567，这样的整体不是，但可以分为两个：123和567。765321也类似。当最长连续数字串有多个时取最后一个。实现如下：
public
static
int
Continumax(String intputStr, StringBuffer outputStr) {
char
[] charArray = intputStr.toCharArray();
StringBuilder sb =
new
StringBuilder();
for
(
int
i =
0
; i < charArray.length; i++) {
if
(Character.isDigit(charArray[i])) {
sb.append(charArray[i]);
}
else
{
sb.append(
","
);
}
}
String[] digitArray = sb.toString().replaceAll(
"(,)+"
,
","
).split(
","
);
//得到数字数组
if
(digitArray.length <=
1
) {
System.out.println(
"没有数字串！"
);
return
0
;
}
List<String> digitList =
new
ArrayList<String>(Arrays.asList(digitArray));
//转化为list方便操作
List<String> positiveDigitList = fetchContinueDigitByPositiveSort(digitList,
true
);
//得到正向连续的数字比如1234，345
List<String> backDigitList = fetchContinueDigitByPositiveSort(digitList,
false
);
//得到反向连续的数字比如4321，765
List<String> lastList =
new
ArrayList<String>();
lastList.addAll(positiveDigitList);
lastList.addAll(backDigitList);
int
maxLength =
0
;
String maxValue =
""
;
List<String> endStrList =
new
ArrayList<String>();
for
(String s : lastList) {
//找出最长并且是最后一个的值和长度
if
(s.length() > maxLength) {
maxLength = s.length();
}
}
for
(String s : lastList) {
//找出最长并且是最后一个的值和长度
if
(s.length() == maxLength) {
endStrList.add(s);
}
}
int
startIndex =
0
;
for
(String s : endStrList) {
if
(intputStr.lastIndexOf(s) >= startIndex) {
startIndex = intputStr.lastIndexOf(s);
maxValue = s;
maxLength = s.length();
}
}
System.out.println(
"最大连续数字串为："
+ maxValue);
System.out.println(
"其长度为："
+ maxLength);
return
maxLength;
}
private
static
List<String> fetchContinueDigitByPositiveSort(List<String> digitList,
boolean
isPositive) {
List<String> lastDigitList =
new
ArrayList<String>();
for
(String s : digitList) {
if
(s.equals(
""
)) {
continue
;
}
char
[] charArray = s.toCharArray();
int
start = Integer.parseInt(String.valueOf(charArray[
0
]));
int
begin = Integer.parseInt(String.valueOf(charArray[
0
]));
int
startIndex =
0
;
if
(charArray.length ==
1
) {
lastDigitList.add(String.valueOf(start));
return
lastDigitList;
}
for
(
int
j =
1
; j < charArray.length; j++) {
if
(isPositive) {
if
(begin +
1
== Integer.parseInt(String.valueOf(charArray[j])) && j != charArray.length -
1
) {
begin = begin +
1
;
continue
;
}
}
else
{
if
(begin -
1
== Integer.parseInt(String.valueOf(charArray[j])) && j != charArray.length -
1
) {
begin = begin -
1
;
continue
;
}
}
begin = Integer.parseInt(String.valueOf(charArray[j]));
if
(start == begin) {
lastDigitList.add(String.valueOf(start));
}
else
if
(j == charArray.length -
1
&& ((isPositive && Integer.parseInt(String.valueOf(charArray[j])) -
1
== Integer.parseInt(String.valueOf(charArray[j -
1
])))
|| (Integer.parseInt(String.valueOf(charArray[j])) +
1
== Integer.parseInt(String.valueOf(charArray[j -
1
]))))) {
lastDigitList.add(String.valueOf(charArray).substring(startIndex, j +
1
));
}
else
{
lastDigitList.add(String.valueOf(charArray).substring(startIndex, j));
if
(j == charArray.length -
1
) {
lastDigitList.add(String.valueOf(charArray[j]));
}
}
start = begin;
startIndex = j;
}
}
return
lastDigitList;
}
public
static
void
main(String[] arg) {
Continumax(
"54321test123457 "
,
null
);
}