最大サブシーケンスの合計

package com.alipay.math.base;

/**
 *  
 * 
 * @author xu.le
 *
 */
public class MaxSubsequenceSum {
	
	 static int  seqStart=0;
	 static int  seqEnd=0;

	/**
	 *  O(n )
	 * @param a
	 * @return
	 */
	public static int maxSubsequenceSum(int[] a){
		int maxSum=0;// 
		 
		for(int i=0;i<a.length;i++){
			int tempSum=0;// 			
			for(int j=i;j<a.length;j++){
				tempSum+=a[j];
				if(tempSum>maxSum){
					maxSum=tempSum;
					seqStart=i;
					seqEnd=j;
				}
			}
		} 
		return maxSum;
	}
	
	/**
	 *  O(n)
	 * @param a
	 * @return
	 */
	public static int maxSubsequenceSumAdvance(int[] a){
		int maxSum=0;
		int tempSum=0;
		int count=0;
		
		for(int i=0,j=0;i<a.length;j++){
			tempSum+=a[j];
			
			if(tempSum>maxSum){
				maxSum=tempSum;
				if(count==0)
					seqStart=i;
				seqEnd=j;
				count++;
			}else {
				if(tempSum<0)
					tempSum=0;
			}
			i=j+1;	
		} 
		return maxSum;
	}
	
	public static void main(String args[]){
		int[] i={-2,11,-4,13,-5,2};
		int[] j={1,-3,4,-2,-1,6};
		int maxSum=maxSubsequenceSumAdvance(i);
		System.out.println("maxSum："+maxSum);
 
		System.out.println("seqStart："+i[seqStart]);
		System.out.println("seqEnd:"+i[seqEnd]);
	}
}