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SplitIntoFibonacci.java
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SplitIntoFibonacci.java
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package com.leetcode.medium;
import java.util.ArrayList;
import java.util.List;
public class SplitIntoFibonacci {
private List<Integer> res = new ArrayList<>();
public List<Integer> splitIntoFibonacci(String S) {
trackBack(S, 0, new ArrayList<>());
return res;
}
private void trackBack(String s, int index, List<Integer> list) {
//题目可能有多种组合
if (res.size() > 0) {
return;
}
//集合里元素少于两个的时候 直接加进去
if (list.size() > 2) {
//如果所有字符都使用了并且满足斐波那契数列的性质
if (checkStr(s, list) && checkIsFib(list)) {
res.addAll(list);
return;
}
//如果剩下的字符串不是以集合里最后两个数的和开头 直接返回
if (!s.substring(index).startsWith(String.valueOf(list.get(list.size() - 1) + list.get(list.size() - 2)))) {
return;
}
}
for (int i = 0; i <= s.length() - index; i++) {
if (index + i <= s.length() && !s.substring(index, index + i).equals("")) {
String str = s.substring(index, index + i);
//判断整型是否溢出
if (str.length() > 10 || Long.valueOf(str) > Integer.MAX_VALUE) {
break;
}
list.add(Integer.valueOf(str));
trackBack(s, index + i, list);
list.remove(list.size() - 1);
}
}
}
private boolean checkStr(String s, List<Integer> list) {
StringBuilder sb = new StringBuilder();
for (int num : list) {
sb.append(num);
}
return sb.toString().equals(s);
}
private boolean checkIsFib(List<Integer> list) {
for (int i = 0; i < list.size() - 2; i++) {
if (list.get(i) + list.get(i + 1) != list.get(i + 2)) {
return false;
}
}
return true;
}
}