寻找数组的中心索引

int pivotIndex(int* nums, int numsSize){
    int sum = 0,left=0;
    for(int i =0; i<numsSize;++i){
        sum+=nums[i];
    }
    int j;
    for(j=0;j<numsSize;++j){
        left+=nums[j];
        if(sum==left)
            return j;
        sum-=nums[j];
    }
    return -1;
}