Minimum Size Subarray Sum

Minimum Size Subarray Sum

问题:

Given an array of n positive integers and a positive integer s, find the minimal length of a subarray of which the sum ≥ s. If there isn't one, return 0 instead.

For example, given the array [2,3,1,2,4,3] and s = 7,
the subarray [4,3] has the minimal length under the problem constraint.

思路:

  双指针

我的代码:

public class Solution {

    public int minSubArrayLen(int s, int[] nums) {

        if(nums==null || nums.length==0)    return 0;

        int minLen = Integer.MAX_VALUE;

        int len = nums.length;

        int tmpSum = 0;

        

        for(int i=0,j=0; j<len; j++)

        {

            tmpSum += nums[j];

            if(tmpSum >= s)

            {

                while(i <= j)

                {

                    tmpSum -= nums[i];

                    if(tmpSum < s) 

                    {

                        tmpSum += nums[i];

                        break;    

                    }

                    else i++;

                }

                minLen = Math.min(minLen, j-i+1);

            }

        }

        

        return minLen==Integer.MAX_VALUE ? 0 : minLen;

    }

}
View Code

学习之处:

  • 双指针的用处在于,后面的指针用于确定下界,前面的指针用于确定上界,然后前面的指针一直再向后指针靠近,尽量压缩之间的距离,也就是要求得的距离
  • 明明规划,i 变成start j变成end 更好一点
  • 改掉自己的坏习惯,稳住心态,不焦虑

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