p151 寻找数组的中心索引(leetcode 724)

一：解题思路

Time:O(n),Space:O(1)

二：完整代码示例 (C++版和Java版)

C++:

class Solution {
public:
    int pivotIndex(vector<int>& nums) 
    {
        if (nums.size() == 0) return -1;
        int sum = 0;
        int total = 0;

        for (int num : nums) total += num;

        for (int i = 0; i < nums.size(); i++)
        {
            if (total - sum - nums[i] == sum) return i;
            sum += nums[i];
        }

        return -1;
    }
};

Java:

class Solution {
        public int pivotIndex(int[] nums) 
        {
               if(nums==null || nums.length==0) return -1;
               int sum=0;
               int total=0;
               
               for(int num:nums) total+=num;
               
               for(int i=0;i<nums.length;i++)
               {
                   if(total-sum-nums[i]==sum) return i;
                   sum+=nums[i];
               }
               
               return -1;
        }
    }