一. 題目描述
Note: This is an extension of House Robber.
After robbing those houses on that street, the thief has found himself a new place for his thievery so that he will not get too much attention. This time, all houses at this place are arranged in a circle. That means the first house is the neighbor of the last one. Meanwhile, the security system for these houses remain the same as for those in the previous street.
Given a list of non-negative integers representing the amount of money of each house, determine the maximum amount of money you can rob tonight without alerting the police.
二. 題目分析
該House Robber的升級版，只是增加了一點條件，即第一個element 和最後一個element不能同時出現，則需分為兩種情況：
第一種情況: 不包括最後一個element；
第二種情況: 不包括第一個element；
兩者的最大值即為全局最大值。
三. 示例代碼
class Solution {
public:
int rob(vector& nums) {
if (nums.size() == 0) return 0;
if (nums.size() == 1) return nums[0];
return max(rob(nums, 0, nums.size()-1), rob(nums, 1, nums.size()));
}
int rob(vector &nums, int start, int end) {
int a = 0, b = 0;
for (int i = start; i < end; i++) {
int m = max(b, a+nums[i]);
a = b;
b = m;
}
return b;
}
};
四. 小結
無
