/* c++ STL is much nore than what i think before in these aspects:
* initializer for node element in struct node;
* compare function in struct : overload operation
* index not iterator used in this function.
*/
class Solution {
public:
struct node{
int value;
int order;
node(int v,int index):value(v), order(index){}
};
struct {
bool operator()(node a, node b){ return a.value<=b.value; }
}compare;
vector<int> twoSum(vector<int>& nums, int target) { vector<int>re;
vector<node>sor;
for(int i=;i<nums.size();i++)sor.push_back(node(nums[i],i));
sort(sor.begin(),sor.end(),compare);
for(int tmp,i=,j=sor.size()-;i<j;)
{
tmp=sor[i].value+sor[j].value;
if(tmp== target)
{
re.push_back(sor[i].order);
re.push_back(sor[j].order);
break;
}
else if(tmp < target)i++;
else j--;
}
return re;
} };
look the solution in java from explantation on leetcode
/* so beautiful and clean
* hashmap..........
*/
public int[] twoSum(int[] nums, int target) {
Map<Integer, Integer> map = new HashMap<>();
for (int i = 0; i < nums.length; i++) {
int complement = target - nums[i];
if (map.containsKey(complement)) {
return new int[] { map.get(complement), i };
}
map.put(nums[i], i);
}
throw new IllegalArgumentException("No two sum solution");
}