Candy

Desicription

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:

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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:

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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.

Solution

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class Solution {
public:
int candy(vector<int>& ratings) {
vector<int> candy(ratings.size(), 1);
for(int i = 1; i < ratings.size(); i++)
if(ratings[i] > ratings[i-1])
candy[i] = candy[i-1] + 1;
for(int i = ratings.size()-1; i >= 1; i--)
if(ratings[i-1] > ratings[i])
candy[i-1] = max(candy[i-1], candy[i] + 1);
int res = 0;
for(auto it : candy)
res += it;
return res;
}
};