The Twosum of Leetcode

Topic:

Given an array of integers, find the numbers such that they add up to a specific target number.

The function twosum should return indices of the numbers such that they add up to the target, where index1 must is Les S than Index2. Please note that your returned answers (both Index1 and INDEX2) is not zero-based.

You may assume this each input would has exactly one solution.

Input:numbers={2, 7, one, A, target=9
Output:index1=1, index2=2

C + + Solution one (traditional method, runtime:19 ms):

1 structNode2 {3     intnum;4     intPos;5 };6 7 BOOLCMP (Node a,node B)8 {9     returna.num<B.num;Ten } One  A  - classSolution { -  Public: thevector<int> Twosum (vector<int> &numbers,inttarget) { -      -vector<int>result; -Vector<node>tmp; + Node A; -      +      for(inti =0; I<numbers.size (); i++) A     { atA.pos = i+1; -A.num =Numbers[i]; - Tmp.push_back (a); -     } -                  - sort (Tmp.begin (), Tmp.end (), CMP); in     intj = tmp.size ()-1; -     intTmpvalue =0; to      +      for(inti =0;i<tmp.size ();) -     { theTmpvalue = tmp[i].num+Tmp[j].num; *         if(tmpvalue==target) $         {Panax Notoginseng             if(tmp[i].pos<Tmp[j].pos) -             { the Result.push_back (tmp[i].pos); + Result.push_back (tmp[j].pos); A             } the             Else +             { - Result.push_back (tmp[j].pos); $ Result.push_back (tmp[i].pos); $             } -              -              Break; the         } -         Else if(tmpvalue>target)Wuyi         { thej--; -         } Wu         Else -         { Abouti++; $         } -     } -      -         returnresult; A     } +};

C + + Solution II (ingenious method, runtime:35 ms):

1 classSolution {2  Public:3vector<int> Twosum (vector<int> &numbers,inttarget) {4         inti, sum;5vector<int>results;6map<int,int>Hmap;7          for(i=0; I<numbers.size (); i++){8             if(!Hmap.count (Numbers[i])) {9Hmap.insert (pair<int,int>(Numbers[i], i));Ten             } One             if(Hmap.count (target-Numbers[i])) { A                 intn=hmap[target-Numbers[i]]; -                 if(n<i) { -Results.push_back (n+1); theResults.push_back (i+1); -                     returnresults; -                 } -  +             } -         } +         returnresults; A     } at};

The Twosum of Leetcode