# 135. Candy (Hard)

https://leetcode.com/problems/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.
```

## Solutions

``````class Solution {
public int candy(int[] ratings) {
int len = ratings.length;
int[] candy = new int[len];

// Each kid at least is allocated 1 candy
for (int i = 0; i < len; i++) {
candy[i] = 1;
}

// traverse from left to right, for each ascending rating pair, allocate one
// more candy to the right kid who carries larger value.
for (int i = 1; i < len; i++) {
if (ratings[i] > ratings[i - 1]) {
candy[i] = candy[i - 1] + 1;
}
}

// similar with above operations, scan from right to left
for (int i = len - 2; i >= 0; i--) {
if ((ratings[i] > ratings[i + 1]) && (candy[i] <= candy[i + 1])) {
candy[i] = candy[i + 1] + 1;
}
}

int num = 0;
for (int i = 0; i < len; i++) {
num += candy[i];
}

return num;
}
}
``````

## Incorrect Solutions

### References

https://www.programcreek.com/2014/03/leetcode-candy-java/