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LC 377. Combination Sum IV

时间:2019-01-13 21:41:39      阅读:145      评论:0      收藏:0      [点我收藏+]

标签:hat   edit   etc   integer   solution   output   his   enc   pbr   

 

Given an integer array with all positive numbers and no duplicates, find the number of possible combinations that add up to a positive integer target.

Example:

nums = [1, 2, 3]
target = 4

The possible combination ways are:
(1, 1, 1, 1)
(1, 1, 2)
(1, 2, 1)
(1, 3)
(2, 1, 1)
(2, 2)
(3, 1)

Note that different sequences are counted as different combinations.

Therefore the output is 7.

 

Follow up:
What if negative numbers are allowed in the given array?
How does it change the problem?
What limitation we need to add to the question to allow negative numbers?

Credits:
Special thanks to @pbrother for adding this problem and creating all test cases.

 

Given an integer array with all positive numbers and no duplicates, find the number of possible combinations that add up to a positive integer target.

Example:

nums = [1, 2, 3]
target = 4

The possible combination ways are:
(1, 1, 1, 1)
(1, 1, 2)
(1, 2, 1)
(1, 3)
(2, 1, 1)
(2, 2)
(3, 1)

Note that different sequences are counted as different combinations.

Therefore the output is 7.

 

Follow up:
What if negative numbers are allowed in the given array?
How does it change the problem?
What limitation we need to add to the question to allow negative numbers?

Credits:
Special thanks to @pbrother for adding this problem and creating all test cases.

 

 

Runtime: 2 ms, faster than 80.43% of Java online submissions for Combination Sum IV.

class Solution {
  public int combinationSum4(int[] nums, int target) {
    int[] dp = new int[target+1];
    dp[0] = 1;
    for(int i=0; i<dp.length; i++){
      for(int j=0; j<nums.length; j++){
        if(i >= nums[j]){
          dp[i] += dp[i - nums[j]];
        }
      }
    }
    return dp[target];
  }
}

 

LC 377. Combination Sum IV

标签:hat   edit   etc   integer   solution   output   his   enc   pbr   

原文地址:https://www.cnblogs.com/ethanhong/p/10264063.html

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