combination sumS solved. easy with dfs. But:

may need to learn how to deal with the order of strings.

Author: acearth

combination_sum.rb

@@ -0,0 +1,27 @@
+def combination_sum(candidates, target)
+  result=Array.new
+  dfs(candidates, Array.new, 0, target, result)
+  result.each {|re| re.sort!}
+  result.sort
+end
+
+def dfs(nums, tmpNums, curSum, target, result)
+  if target==curSum
+    result.push tmpNums
+    return
+  else
+    for i in 0..nums.size-1
+      if target>=curSum+nums[i]
+        tmpNumsNew=tmpNums.dup
+        tmpNumsNew.push nums[i]
+        dfs(nums[i..-1], tmpNumsNew, curSum+nums[i], target, result)
+      end
+    end
+  end
+end
+
+ar=2, 3, 6, 7
+p combination_sum ar, 7
+ar=[8,7,4,3]
+p combination_sum ar, 11
+

combination_sum2.rb

@@ -0,0 +1,28 @@
+def combination_sum2(candidates, target)
+  result=Array.new
+  dfs(candidates, Array.new, 0, target, result)
+  result.sort!
+  result.uniq #Should I use uniq methed or implement this method?
+end
+
+def dfs(nums, tmpNums, curSum, target, result)
+  for i in 0..nums.size-1
+    if target==curSum+nums[i]
+      tmpNumsNew=tmpNums.dup
+      tmpNumsNew.push nums[i]
+      result.push tmpNumsNew.sort
+    elsif target>curSum+nums[i]
+      tmpNumsNew=tmpNums.dup
+      tmpNumsNew.push nums[i]
+      break if i==nums.size-1
+      dfs(nums[i+1..-1], tmpNumsNew, curSum+nums[i], target, result)
+    end
+  end
+end
+
+ar=2, 3, 6, 7
+p combination_sum ar, 7
+ar=[8, 7, 4, 3]
+p combination_sum ar, 11
+ar=10, 1, 2, 7, 6, 1, 5
+p combination_sum ar, 8

combination_sum3.rb

@@ -0,0 +1,29 @@
+def combination_sum3(k,target)
+  result=Hash.new
+  dfs([1,2,3,4,5,6,7,8,9], Array.new, 0, target, result)
+  res=Array.new
+  result.each{|key,v| res.push key if v==true&&key.size==k}
+  res.sort
+end
+
+def dfs(nums, tmpNums, curSum, target, result)
+  for i in 0..nums.size-1
+    if target==curSum+nums[i]
+      tmpNumsNew=tmpNums.dup
+      tmpNumsNew.push nums[i]
+      result[tmpNumsNew.sort]=true
+    elsif target>curSum+nums[i]
+      tmpNumsNew=tmpNums.dup
+      tmpNumsNew.push nums[i]
+      break if i==nums.size-1
+      dfs(nums[i+1..-1], tmpNumsNew, curSum+nums[i], target, result)
+    end
+  end
+end
+
+ar=2, 3, 6, 7
+p combination_sum3  3,7
+ar=[8, 7, 4, 3]
+p combination_sum3  3,11
+ar=10, 1, 2, 7, 6, 1, 5
+p combination_sum3  3,8