CanPlaceFlowers.cpp

//Suppose you have a long flowerbed in which some of the plots are planted and some are not. However, flowers cannot be planted in adjacent plots - they would compete for water and both would die.
//
//Given a flowerbed (represented as an array containing 0 and 1, where 0 means empty and 1 means not empty), and a number n, return if n new flowers can be planted in it without violating the no-adjacent-flowers rule.
//
//Example 1:
//Input: flowerbed = [1,0,0,0,1], n = 1
//Output: True
//Example 2:
//Input: flowerbed = [1,0,0,0,1], n = 2
//Output: False
//Note:
//The input array won't violate no-adjacent-flowers rule.
//The input array size is in the range of [1, 20000].
//n is a non-negative integer which won't exceed the input array size.

#include<vector>
#include<algorithm>

using namespace std;



class CanPlaceFlowers {
public:
	bool canPlaceFlowers(vector<int>& flowerbed, int n) {
		int cnt = 0;
		int nn = flowerbed.size();
		int cur = 0;
		bool start = flowerbed[0] ? false : true;
		for (int i = 0; i < nn; ++i){
			if (flowerbed[i]){
				if (start){
					cnt += cur / 2;
					start = false;
				}
				else{
					cnt += (cur - 1) / 2;
				}
				cur = 0;
			}
			else{
				++cur;
			}
		}
		//cout<<cur;
		if (!flowerbed[nn - 1]){
			if (start){
				cnt += (cur + 1) / 2;
			}
			else{
				//cout<<cur;
				cnt += cur / 2;
			}

		}
		//cout<<cnt;
		return cnt >= n;
	}
};