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3Sum Closest.cpp
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3Sum Closest.cpp
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class Solution {
private:
int N;
public:
int threeSumClosest(vector<int> &num, int target) {
int differ = 0x7fffffff, ret;
N = num.size();
sort(num.begin(), num.end());
for (int i = 0; i < N; i++) {
int tmpRet = threeSumClosestHelper(num, i, target);
if (abs(tmpRet - target) < differ) {
differ = abs(tmpRet - target);
ret = tmpRet;
}
}
return ret;
}
int threeSumClosestHelper(vector<int> &num, int pos, int target) {
int start = 0, end = N - 1;
int differ = 0x7fffffff, ret = 0;
while (start < end) {
if (pos == start) start++;
if (pos == end) end--;
if (start >= end) break;
int nowv = num[pos] + num[end] + num[start];
if (abs(nowv - target) < differ) {
differ = abs(nowv - target);
ret = nowv;
}
if (nowv == target) return target;
else if (nowv < target) {
start++;
} else {
end--;
}
}
return ret;
}
};