Leetcode: Candy

Leetcode: Candy

There areNChildren 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?

Address: https://oj.leetcode.com/problems/candy/

Algorithm: this problem can be solved by Dynamic Planning, before the exercise in the King of the have met, analysis see my previous article: http://www.cnblogs.com/boostable/p/online_judge_1470_1549_1493_1550.html

Code:

 1 class Solution { 2 public: 3     int candy(vector<int> &ratings) { 4         int n = ratings.size(); 5         vector<int> num_candys(n); 6         if(n == 0) 7             return 0; 8         return subSolution(0,n-1,num_candys,ratings);  9     }10     int subSolution(int s, int e, vector<int> &num_candys,vector<int> &ratings){11         if(s == e){12             num_candys[s] = 1;13             return 1;14         }else{15             int total = 0;16             int mid = (s + e) >> 1;17             int left = subSolution(s,mid,num_candys,ratings);18             int right = subSolution(mid+1,e,num_candys,ratings);19             if(ratings[mid] == ratings[mid+1]){20                 return left + right;21             }else if(ratings[mid] > ratings[mid+1]){22                 if(num_candys[mid] > num_candys[mid+1])23                     return left + right;24                 else{25                     total += (num_candys[mid+1] + 1 - num_candys[mid]);26                     num_candys[mid] = num_candys[mid+1] + 1;27                     int totalAdd = 0;28                     for(int i = mid-1; i >= s; --i){29                         if(ratings[i] <= ratings[i+1] || (ratings[i] > ratings[i+1] && num_candys[i] > num_candys[i+1]))30                             break;31                         else{32                             total += (num_candys[i+1] + 1 - num_candys[i]);33                             num_candys[i] = num_candys[i+1] + 1;34                         }35                     }36                     return left + right + total;37                 }38             }else{39                 if(num_candys[mid] < num_candys[mid+1])40                     return left + right;41                 else{42                     total += (num_candys[mid] + 1 - num_candys[mid+1]);43                     num_candys[mid+1] = num_candys[mid] + 1;44                     for(int i = mid+2; i <= e; ++i){45                         if(ratings[i] <= ratings[i-1] || (ratings[i] > ratings[i-1] && num_candys[i] > num_candys[i-1]))46                             break;47                         else{48                             total += (num_candys[i-1] + 1 - num_candys[i]);49                             num_candys[i] = num_candys[i-1] + 1;50                         }51                     }52                     return left + right + total;53                 }54             }55         }56     }57 };

 

Leetcode: Candy