Given a 0-indexed integer array nums of size n, find the maximum difference between nums[i] and nums[j] (i.e., nums[j] - nums[i]), such that 0 <= i < j < n and nums[i] < nums[j].
Return the maximum difference. If no such i and j exists, return -1.
Example 1:
Input: nums = [7,1,5,4] Output: 4 Explanation: The maximum difference occurs with i = 1 and j = 2, nums[j] - nums[i] = 5 - 1 = 4. Note that with i = 1 and j = 0, the difference nums[j] - nums[i] = 7 - 1 = 6, but i > j, so it is not valid.
Example 2:
Input: nums = [9,4,3,2] Output: -1 Explanation: There is no i and j such that i < j and nums[i] < nums[j].
Example 3:
Input: nums = [1,5,2,10] Output: 9 Explanation: The maximum difference occurs with i = 0 and j = 3, nums[j] - nums[i] = 10 - 1 = 9.
Constraints:
n == nums.length2 <= n <= 10001 <= nums[i] <= 109struct Solution;
impl Solution {
fn maximum_difference(nums: Vec<i32>) -> i32 {
let n = nums.len();
let mut res = -1;
for i in 0..n {
for j in i + 1..n {
if nums[i] < nums[j] {
res = res.max(nums[j] - nums[i]);
}
}
}
res
}
}
#[test]
fn test() {
let nums = vec![7, 1, 5, 4];
let res = 4;
assert_eq!(Solution::maximum_difference(nums), res);
let nums = vec![9, 4, 3, 2];
let res = -1;
assert_eq!(Solution::maximum_difference(nums), res);
let nums = vec![1, 5, 2, 10];
let res = 9;
assert_eq!(Solution::maximum_difference(nums), res);
}