LeetCode 1595 Minimum Cost to Connect Two Groups of Points (动态规划)

题目

题解： 动态规划，用二进制压缩状态，注意分析几种情况，就能推出来正确的状态转移方程。

class Solution {
public:
    int dp[12][4096];
   int connectTwoGroups(vector<vector<int>>& cost) {
	int n = cost.size();
	if (n == 0)
		return 0;
	int m = cost[0].size();

	for (int i = 0; i < n; i++)
	{
		for (int j = 0; j < (1 << m); j++)
		{
			dp[i][j] = INT32_MAX;
			for (int k = 0; k < m; k++)
			{
				if (j & (1 << k))
				{
					if (i != 0 && dp[i - 1][j ^ (1 << k)] != INT32_MAX )
					{
						dp[i][j] = min(dp[i][j], dp[i - 1][j ^ (1 << k)] + cost[i][k]);
					}

					if (i != 0 && (dp[i - 1][j] != INT32_MAX))
					{
						dp[i][j] = min(dp[i][j], dp[i-1][j]+cost[i][k]);
						
					}

					if (i == 0 && (j ^ (1 << k)) == 0)
					{
						dp[i][j] = cost[i][k];
					}
					else
					{
						if (dp[i][j ^ (1 << k)] != INT32_MAX)
						{
							dp[i][j] = min(dp[i][j], dp[i][j ^ (1 << k)] + cost[i][k]);
						}
					}
				}

			}
		}
	}

	return dp[n - 1][(1 << m) - 1];

}
};