public class MaxSubArray
...{
public static void main(String[] args)
...{
ArrayList<int[]> testData = new ArrayList<int[]>();
//这是一些测试用的数组
testData.add(new int[]...{-7,15,2,-5,12,6,-26});
testData.add(new int[]...{1});
testData.add(new int[]...{12, -8, 5, 66, -21, 0,35, -44,7});
testData.add(new int[]...{-100,-100,-100,-100,100});
testData.add(new int[]...{3,73,-95,42,43,29,-30,-87,74,-53,22,74,-91,-1,-27,-8,-14,26,-67,-74});
testData.add(new int[]...{12, -8, 71, -21, 35, -44,7 ,-2000,1999});
testData.add(new int[]...{98,99,-2,-99,100,-99,-2});
testData.add(new int[]...{-2, 11, -4, 13, -5, -2});
testData.add(new int[]...{-1});
for(int[] array:testData)
...{
System.out.println(Arrays.toString(array));
System.out.println("result:"+findMaxSubArray(array));
System.out.println();
}
}
static private SubArray findMaxSubArray(int[] intArray)
...{
//去头，去尾
int bIndex = 0,eIndex = intArray.length-1;
while(intArray[bIndex]<=0 && bIndex+1<intArray.length)...{bIndex++;}
while(intArray[eIndex]<=0 && eIndex-1>=0)...{eIndex--;}
LinkedList<SubArray> saList = new LinkedList<SubArray>();
for(int i=bIndex; i<=eIndex; i++)
...{
saList.add(new SubArray(i,intArray[i]));
}
//合并相邻的属性相似的数据
Iterator<SubArray> iter = saList.iterator();
if(iter.hasNext())
...{
SubArray a = iter.next();
while(iter.hasNext())
...{
SubArray b = iter.next();
if((a.getSum()>=0 && b.getSum()>=0)||(a.getSum()<=0 && b.getSum()<=0))
...{
a.m(b);
iter.remove();
}
else
...{
a = b;
}
}
}
//跨区段合并更大范围的数据
SubArray[] array = new SubArray[saList.size()];
array = saList.toArray(array);
if(array.length>=3)
...{
for(int i=1;i<array.length; i+=2)
...{
SubArray a = array[i-1];
SubArray b = array[i];
SubArray c = array[i+1];
int sum = a.getSum()+b.getSum()+c.getSum();
if( sum > a.getSum() && sum > c.getSum())
...{
a.m(b);
a.m(c);
array[i-1] = null;
array[i] = null;
array[i+1] = a;
}
}
}
//找到sum值最大的一段
SubArray maxSubArray = null;
for(int i=0;i<array.length; i++)
...{
if(null!=array[i])
...{
if(null==maxSubArray || array[i].getSum()>maxSubArray.getSum())
...{
maxSubArray = array[i];
}
}
}
return maxSubArray;
}
/** *//**
* 为了记录原始下标而建立的 子数组 对象
* @author 顾法华，杭州
*
*/
static private class SubArray
...{
int head = -1;
LinkedList<Integer> content;
SubArray(int head,LinkedList<Integer> subArray)
...{
this.head = head;
this.content = subArray;
}
SubArray(int head,int v)
...{
this(head,new LinkedList<Integer>());
content.add(v);
}
public void m(SubArray sa)
...{
content.addAll(sa.content);
}
public int getSum()
...{
int s = 0;
for(int i : content)
...{
s += i;
}
return s;
}
public String toString()
...{
return this.getSum()+" ("+head+"~"+(head+content.size()-1)+") "+content.toString();
}
}
}
//找到这个你看看