LeetCode每日一题_21_04_24(377. 组合总和 IV)

377. 组合总和 Ⅳ

LeetCode每日一题 2021/4/24

//解法1
class Solution{
public:
	int dp[1005];
	int dfs(const vector<int> &nums, int target){
		if(dp[target] != -1) return dp[target];
		int ans = 0;
		for(int i : nums){
			if(i > target) break;
			if(i == target){
				ans++;
				break;
			}
			ans += dfs(nums, target - i);
		}
		dp[target] = ans;
		return ans;
	}
	int combinationSum4(vector<int> &nums, int target){
		sort(nums.begin(), nums.end());
		memset(dp, -1, sizeof dp);
		return dfs(nums, target);
	}
	
};

//解法2
class Solution{
public:
	int combinationSum4(vector<int> &nums, int target){
		unsigned int dp[target + 1];
		memset(dp, 0, sizeof dp);
		dp[0] = 1;
		int len = nums.size();
		for(int i = 0; i <= target; i++){
			for(int j = 0; j < len; j++){
				if(nums[j] <= i) dp[i] += dp[i - nums[j]];
			}
		}
		return dp[target];
	}
	
};