[pull] master from wisdompeak:master #83

Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,20 @@
	using LL = long long;
	class Solution {
	public:
	long long minimumTime(vector<int>& power)
	{
	int n = power.size();
	vector<LL>dp(1<<n, LLONG_MAX/2);
	dp[0] = 0;
	for (int state = 1; state < (1<<n); state++)
	{
	int k = __builtin_popcount(state);
	for (int i=0; i<n; i++)
	{
	if ((state>>i)&1)
	dp[state] = min(dp[state], dp[state- (1<<i)] + (power[i]-1)/k+1);
	}
	}
	return dp[(1<<n)-1];
	}
	};

Show comments View file Open in desktop

Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,16 @@
	### 2403.Minimum-Time-to-Kill-All-Monsters

	本题首先需要知道,并不是将monster按照从小到大排序就是最优解。Example 1 就是一个反例。考虑到monster的个数只有17,说明所有的状态数是`2^17=131072`,使用状态压缩dp的复杂度是可以接受的。

	我们令二进制数state表示哪些怪兽被消灭,dp[state]表示消灭这些怪兽所需要的最少天数,因此状态转移方程取决于state里面哪一个是最后一只被消灭的怪兽,穷举一下即可:
	```cpp
	int k = __builtin_popcount(state); // state所对应的怪兽数目
	for (int i=0; i<n; i++)
	{
	if (bit i属于state的子集)
	dp[state] = min{ dp[state - (1<<i)] + 怪兽i作为第k个目标所需要花费的时间}
	}
	```
	最后返回`dp[(1<<n)-1]`.

	整体的时间复杂度是`2^17*17 = 2e6`。

1 change: 1 addition & 0 deletions Readme.md

Show comments View file Open in desktop

Original file line number	Diff line number	Diff line change
Expand Up		@@ -791,6 +791,7 @@
		[1931.Painting-a-Grid-With-Three-Different-Colors](https://github.com/wisdompeak/LeetCode/tree/master/Dynamic_Programming/1931.Painting-a-Grid-With-Three-Different-Colors) (M+)
		[1994.The-Number-of-Good-Subsets](https://github.com/wisdompeak/LeetCode/tree/master/Dynamic_Programming/1994.The-Number-of-Good-Subsets) (H)
		[2184.Number-of-Ways-to-Build-Sturdy-Brick-Wall](https://github.com/wisdompeak/LeetCode/tree/master/Dynamic_Programming/2184.Number-of-Ways-to-Build-Sturdy-Brick-Wall) (H-)
	[2403.Minimum-Time-to-Kill-All-Monsters](https://github.com/wisdompeak/LeetCode/tree/master/Dynamic_Programming/2403.Minimum-Time-to-Kill-All-Monsters) (M+)
		* ``枚举集合的子集``
		[1494.Parallel-Courses-II](https://github.com/wisdompeak/LeetCode/tree/master/Dynamic_Programming/1494.Parallel-Courses-II) (H)
		[1655.Distribute-Repeating-Integers](https://github.com/wisdompeak/LeetCode/tree/master/Dynamic_Programming/1655.Distribute-Repeating-Integers) (H)
Expand Down

Navigation Menu