carloscn
commented
1 year ago Analysis
pub fn find_middle_index(nums: Vec<i32>) -> i32
{
if nums.len() < 3 {
return -1;
}
let mut ret:i32 = -1;
let mut sum_left:i32;
let mut sum_right:i32;
let left:usize = 0;
let right:usize = nums.len();
for mid in 1..nums.len() {
sum_left = 0;
sum_right = 0;
for i in left..mid {
sum_left += nums[i];
}
for i in (mid + 1)..right {
sum_right += nums[i];
}
if sum_left == sum_right {
ret = mid as i32;
break;
}
}
return ret;
}
Decription
Given a 0-indexed integer array nums, find the leftmost middleIndex (i.e., the smallest amongst all the possible ones).
A middleIndex is an index where nums[0] + nums[1] + ... + nums[middleIndex-1] == nums[middleIndex+1] + nums[middleIndex+2] + ... + nums[nums.length-1].
If middleIndex == 0, the left side sum is considered to be 0. Similarly, if middleIndex == nums.length - 1, the right side sum is considered to be 0.
Return the leftmost middleIndex that satisfies the condition, or -1 if there is no such index.
Example 1:
Input: nums = [2,3,-1,8,4] Output: 3 Explanation: The sum of the numbers before index 3 is: 2 + 3 + -1 = 4 The sum of the numbers after index 3 is: 4 = 4
Example 2:
Input: nums = [1,-1,4] Output: 2 Explanation: The sum of the numbers before index 2 is: 1 + -1 = 0 The sum of the numbers after index 2 is: 0
Example 3:
Input: nums = [2,5] Output: -1 Explanation: There is no valid middleIndex.
Constraints:
Note: This question is the same as 724: https://leetcode.com/problems/find-pivot-index/