135. Candy
There are N children standing in a line. Each child is assigned a rating value.
You are giving candies to these children subjected to the following requirements:
- Each child must have at least one candy.
- Children with a higher rating get more candies than their neighbors.
What is the minimum candies you must give?
Example 1:
Input: [1,0,2] Output: 5 Explanation: You can allocate to the first, second and third child with 2, 1, 2 candies respectively.
Example 2:
Input: [1,2,2]
Output: 4
Explanation: You can allocate to the first, second and third child with 1, 2, 1 candies respectively.
The third child gets 1 candy because it satisfies the above two conditions.
Rust Solution
struct Solution;
impl Solution {
fn candy(ratings: Vec<i32>) -> i32 {
let n = ratings.len();
let mut count: Vec<i32> = vec![1; n];
for i in 1..n {
if ratings[i] > ratings[i - 1] {
count[i] = count[i].max(count[i - 1] + 1);
}
}
for i in (0..n - 1).rev() {
if ratings[i] > ratings[i + 1] {
count[i] = count[i].max(count[i + 1] + 1);
}
}
count.into_iter().sum()
}
}
#[test]
fn test() {
let ratings = vec![1, 0, 2];
let res = 5;
assert_eq!(Solution::candy(ratings), res);
let ratings = vec![1, 2, 2];
let res = 4;
assert_eq!(Solution::candy(ratings), res);
let ratings = vec![1, 3, 2, 2, 1];
let res = 7;
assert_eq!(Solution::candy(ratings), res);
}
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