Sum(C++) - 编程开发习题

sum(c++) - 开发习题。

given an arraynumsofnintegers and an integertarget, are there elementsa,b,c, anddinnumssuch thata+b+c+d=target find all unique quadruplets in the array which gives the sum oftarget.

class solution {
public:
vector> foursum(vector& nums, int target)
{
vector> ret;
int n=nums.size();
if(n<4)
return ret;
sort(nums.begin(),nums.end());
for(int i=0;i<=n-4;i++)
{
for(int j=i+1;j<=n-3;j++)
{
int m=j+1;
int k=n-1;
while(m
{
if(nums[i]+nums[j]+nums[m]+nums[k]
m++;
else if(nums[i]+nums[j]+nums[m]+nums[k]>target)
k--;
else
{
ret.push_back({nums[i],nums[j],nums[m],nums[k]});
m++;
k--;
while(j
m++;
while(j
k--;
}
}
while(nums[j]==nums[j+1])
j++;
}
while(nums[i]==nums[i+1])
i++;
}
return ret;
}
};