lintcode-medium-Continuous Subarray Sum

Posted 2020-06-23 哥布林工程师

Given an integer array, find a continuous subarray where the sum of numbers is the biggest. Your code should return the index of the first number and the index of the last number. (If their are duplicate answer, return anyone)

Give [-3, 1, 3, -3, 4], return [1,4].

 

这道题和maximum subarray基本一样，区别在于需要记录index

public class Solution {
    /**
     * @param A an integer array
     * @return  A list of integers includes the index of the first number and the index of the last number
     */
    public ArrayList<Integer> continuousSubarraySum(int[] A) {
        // Write your code here
        
        ArrayList<Integer> result = new ArrayList<Integer>();
        
        if(A == null || A.length == 0)
            return result;
        
        int index1 = 0;
        int index2 = 0;
        int sum = A[0];
        int max = A[0];
        int res1 = 0;
        int res2 = 0;
        
        for(int i = 1; i < A.length; i++){
            if(sum < 0){
                sum = 0;
                index1 = i;
                index2 = i;
            }
            
            sum += A[i];

            if(sum > max){
                max = sum;
                index2 = i;
                res1 = index1;
                res2 = index2;
            }
        }
        
        result.add(res1);
        result.add(res2);
        return result;
    }
}