leetcode - 135. 分发糖果

#include 
#include 
using namespace std;

// 1：ratings[i] > ratings[i-1]   从左往右 
// 2: ratings[i] > ratings[i+1]   从右往左 
int candy(vector& ratings) {
	int n = ratings.size();
	if(n == 1){
		return 1;
	}
	int pre, cur;
	int count = 0;
	vector left(n);
	if(ratings[0] > ratings[1]){
		pre = 2;
	}else{
		pre = 1;
	}
	left[0] = pre; 
	for(int i = 1; i < n; i++){
		if(ratings[i] > ratings[i-1]){
			cur = pre + 1;
		}else{
			cur = 1;
		}
		pre = cur;
		left[i] = pre;
	} 
	if(ratings[n-1] > ratings[n-2]){
		pre = 2;
	}else{
		pre = 1;
	}
	count += max(pre, left[n-1]);
	for(int i = n - 2; i >= 0; i--){
		if(ratings[i] > ratings[i+1]){
			cur = pre + 1;
		}else{
			cur = 1;
		}
		pre = cur;
		count += max(pre, left[i]);
	}
	return count;
}

int main(){
	int n, res;
	cin>>n;
	vector ratings(n);
	for(int i = 0; i < n; i++){
		cin>>ratings[i];
	}
	res = candy(ratings);
	cout<