leetcode: 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?

先从左到右遍历，如果i+1个rating大于i，糖果加1；再从右到左遍历，如果i个rating小于i-1个rating且i糖果大于等于i-1糖果，则i-1糖果等于i糖果加1

画图，思考，尝试

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