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Copy path3Sum_Closest.cpp
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86 lines (75 loc) · 1.56 KB
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#include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <algorithm>
using namespace std;
/************* TLE Version ***********************
int threeSumClosest(vector <int> &num, int target) {
int delta = 0x7fffffff;
int ret = 0;
for (int i = 0; i < num.size(); ++i) {
int sum = 0;
for (int j = i+1; j < num.size(); ++j) {
for (int k = j+1; k < num.size(); ++k) {
sum = num[i] + num[j] + num[k];
//cout << "sum " << sum << endl;
if (abs(sum-target) < delta) {
ret = sum;
delta = abs(sum-target);
}
}
}
}
return ret;
}
*/
int twoSumClosest(int target, int skip, vector <int> num) {
int small = 0;
int big = num.size()-1;
int delta = 0x7fffffff;
int ret;
while (small < big) {
if (small == skip) {
small ++;
} else if (big == skip) {
big--;
}
if (small < big) {
int sum = num[small] + num[big];
if (abs(sum-target) < delta) {
ret = sum;
delta = abs(sum-target);
}
if (sum > target) {
big--;
} else if (sum < target) {
small++;
} else {
break;
}
}
}
return ret;
}
int threeSumClosest(vector <int> &num, int target) {
sort(num.begin(), num.end());
int ret = 0;
int delta = 0x7fffffff;
for (int i = 0; i < num.size(); ++i) {
int sum = num[i] + twoSumClosest(target-num[i], i, num);
if (abs(sum-target) < delta) {
ret = sum;
delta = abs(sum-target);
}
}
return ret;
}
int main() {
int arr[] = {-1, 2, 1, -4};
vector <int> input(arr, arr+4);
int target;
cin >> target;
cout << threeSumClosest(input, target) << endl;
return 0;
}