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algorithms: (3/4)Sum(Closest): Improve code readability
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This just makes the code easier to follow.

Signed-off-by: RJ Trujillo <certifiedblyndguy@gmail.com>
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@haoel
RJ Trujillo authored and haoel committed Jan 16, 2020
1 parent e626292 commit bd9928b
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Showing 3 changed files with 70 additions and 68 deletions.
71 changes: 36 additions & 35 deletions algorithms/cpp/3Sum/3Sum.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
#include <vector>
#include <set>
#include <algorithm>

using namespace std;


Expand All @@ -47,7 +48,7 @@ using namespace std;
vector<vector<int> > threeSum(vector<int> &num) {

vector< vector<int> > result;
if(num.size()==0 || num.size()==1 || num.size() == 2) return result;
if(num.size() == 0 || num.size() == 1 || num.size() == 2) return result;

//sort the array, this is the key
sort(num.begin(), num.end());
Expand All @@ -56,14 +57,14 @@ vector<vector<int> > threeSum(vector<int> &num) {

for (int i=0; i<n-2; i++) {
//skip the duplication
if (i>0 && num[i-1]==num[i]) continue;
if (i > 0 && num[i - 1] == num[i]) continue;
int a = num[i];
int low = i+1;
int high = n-1;
while ( low < high ) {
int low = i + 1;
int high = n - 1;
while (low < high) {
int b = num[low];
int c = num[high];
if (a+b+c == 0) {
if (a + b + c == 0) {
//got the soultion
vector<int> v;
v.push_back(a);
Expand All @@ -72,17 +73,17 @@ vector<vector<int> > threeSum(vector<int> &num) {
result.push_back(v);
// Continue search for all triplet combinations summing to zero.
//skip the duplication
while(low<n-1 && num[low]==num[low+1]) low++;
while(high>0 && num[high]==num[high-1]) high--;
while(low < n - 1 && num[low] == num[low + 1]) low++;
while(high > 0 && num[high] == num[high - 1]) high--;
low++;
high--;
} else if (a+b+c > 0) {
//skip the duplication
while(high>0 && num[high]==num[high-1]) high--;
while(high > 0 && num[high] == num[high - 1]) high--;
high--;
} else{
} else {
//skip the duplication
while(low<n-1 && num[low]==num[low+1]) low++;
while(low < n - 1 && num[low] == num[low + 1]) low++;
low++;
}
}
Expand All @@ -98,21 +99,21 @@ int sum(vector<int>& v);
vector<vector<int> > threeSum2(vector<int> &num) {
vector< vector<int> > result;
vector< vector<int> > r = combination(num, 3);
for (int i=0; i<r.size(); i++){
if (isSumZero(r[i])){
for (int i = 0; i < r.size(); i++) {
if (isSumZero(r[i])) {
result.push_back(r[i]);
}
}
return result;
}

bool isSumZero(vector<int>& v){
return sum(v)==0;
bool isSumZero(vector < int>& v) {
return sum(v) == 0;
}

int sum(vector<int>& v){
int s=0;
for(int i=0; i<v.size(); i++){
int sum(vector<int>& v) {
int s = 0;
for(int i = 0; i < v.size(); i++) {
s += v[i];
}
return s;
Expand All @@ -123,39 +124,39 @@ vector<vector<int> > combination(vector<int> &v, int k) {
vector<vector<int> > result;
vector<int> d;
int n = v.size();
for (int i=0; i<n; i++){
d.push_back( (i<k) ? 1 : 0 );
for (int i = 0; i < n; i++) {
d.push_back( (i < k) ? 1 : 0 );
}

//1) from the left, find the [1,0] pattern, change it to [0,1]
//2) move all of the 1 before the pattern to the most left side
//3) check all of 1 move to the right
while(1){
while(1) {
vector<int> tmp;
for(int x=0; x<n; x++){
for(int x = 0; x < n; x++) {
if (d[x]) tmp.push_back(v[x]);
}
sort(tmp.begin(), tmp.end());
result.push_back(tmp);
//step 1), find [1,0] pattern
int i;
bool found = false;
int ones =0;
for(i=0; i<n-1; i++){
int ones = 0;
for(i = 0; i < n - 1; i++) {

if (d[i]==1 && d[i+1]==0){
d[i]=0; d[i+1]=1;
if (d[i] == 1 && d[i + 1] == 0) {
d[i] = 0; d[i + 1] = 1;
found = true;
//step 2) move all of right 1 to the most left side
for (int j=0; j<i; j++){
d[j]=( ones > 0 ) ? 1 : 0;
for (int j = 0; j < i; j++) {
d[j] = ( ones > 0 ) ? 1 : 0;
ones--;
}
break;
}
if (d[i]==1) ones++;
if (d[i] == 1) ones++;
}
if (!found){
if (!found) {
break;
}

Expand All @@ -166,9 +167,9 @@ vector<vector<int> > combination(vector<int> &v, int k) {

void printMatrix(vector<vector<int> > &matrix)
{
for(int i=0; i<matrix.size(); i++){
for(int i = 0; i < matrix.size(); i++) {
printf("{");
for(int j=0; j< matrix[i].size(); j++) {
for(int j = 0; j < matrix[i].size(); j++) {
printf("%3d ", matrix[i][j]) ;
}
printf("}\n");
Expand All @@ -179,9 +180,9 @@ void printMatrix(vector<vector<int> > &matrix)

int main()
{
//int a[] = {-1, 0, 1, 2, -1, 1, -4};
int a[] = {-1, 1, 1, 1, -1, -1, 0,0,0};
vector<int> n(a, a+sizeof(a)/sizeof(int));
//int a[] = { -1, 0, 1, 2, -1, 1, -4 };
int a[] = { -1, 1, 1, 1, -1, -1, 0,0,0 };
vector<int> n(a, a + sizeof(a)/sizeof(int));
vector< vector<int> > result = threeSum(n);
printMatrix(result);
return 0;
Expand Down
24 changes: 12 additions & 12 deletions algorithms/cpp/3SumClosest/3SumClosest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
#include <vector>
#include <set>
#include <algorithm>

using namespace std;

#define INT_MAX 2147483647
Expand Down Expand Up @@ -53,34 +54,33 @@ int threeSumClosest(vector<int> &num, int target) {

for (int i=0; i<n-2; i++) {
//skip the duplication
if (i>0 && num[i-1]==num[i]) continue;
if (i > 0 && num[i - 1] == num[i]) continue;
int a = num[i];
int low = i+1;
int high = n-1;
int low = i + 1;
int high = n - 1;
//convert the 3sum to 2sum problem
while ( low < high ) {
while (low < high) {
int b = num[low];
int c = num[high];
int sum = a+b+c;
int sum = a + b + c;
if (sum - target == 0) {
//got the final soultion
return target;
} else {

//tracking the minmal distance
if (abs(sum-target) < distance ) {
if (abs(sum - target) < distance ) {
distance = abs(sum - target);
result = sum;
}

if (sum -target> 0) {
if (sum - target > 0) {
//skip the duplication
while(high>0 && num[high]==num[high-1]) high--;
while(high > 0 && num[high] == num[high - 1]) high--;
//move the `high` pointer
high--;
} else {
//skip the duplication
while(low<n && num[low]==num[low+1]) low++;
while(low < n && num[low] == num[low + 1]) low++;
//move the `low` pointer
low++;
}
Expand All @@ -96,8 +96,8 @@ int threeSumClosest(vector<int> &num, int target) {

int main()
{
int a[] = {-1, 2, 1, -4};
vector<int> n(a, a+sizeof(a)/sizeof(int));
int a[] = { -1, 2, 1, -4 };
vector<int> n(a, a + sizeof(a)/sizeof(int));
int target = 1;
cout << threeSumClosest(n, target) << endl;
return 0;
Expand Down
43 changes: 22 additions & 21 deletions algorithms/cpp/4Sum/4Sum.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

vector<vector<int> > threeSum(vector<int> num, int target);
Expand All @@ -36,15 +37,15 @@ vector<vector<int> > threeSum(vector<int> num, int target);

vector<vector<int> > fourSum(vector<int> &num, int target) {
vector< vector<int> > result;
if (num.size()<4) return result;
if (num.size() < 4) return result;
sort( num.begin(), num.end() );
for(int i=0; i<num.size()-3; i++) {

for(int i = 0; i < num.size() - 3; i++) {
//skip the duplication
if (i>0 && num[i-1]==num[i]) continue;
if (i > 0 && num[i - 1] == num[i]) continue;
vector<int> n(num.begin()+i+1, num.end());
vector<vector<int> > ret = threeSum(n, target-num[i]);
for(int j=0; j<ret.size(); j++){
for(int j = 0; j < ret.size(); j++) {
ret[j].insert(ret[j].begin(), num[i]);
result.push_back(ret[j]);
}
Expand All @@ -61,16 +62,16 @@ vector<vector<int> > threeSum(vector<int> num, int target) {

int n = num.size();

for (int i=0; i<n-2; i++) {
for (int i = 0; i < n - 2; i++) {
//skip the duplication
if (i>0 && num[i-1]==num[i]) continue;
if (i > 0 && num[i - 1] == num[i]) continue;
int a = num[i];
int low = i+1;
int high = n-1;
while ( low < high ) {
int low = i + 1;
int high = n - 1;
while (low < high) {
int b = num[low];
int c = num[high];
if (a+b+c == target) {
if (a + b + c == target) {
//got the soultion
vector<int> v;
v.push_back(a);
Expand All @@ -79,17 +80,17 @@ vector<vector<int> > threeSum(vector<int> num, int target) {
result.push_back(v);
// Continue search for all triplet combinations summing to zero.
//skip the duplication
while(low<n && num[low]==num[low+1]) low++;
while(high>0 && num[high]==num[high-1]) high--;
while(low < n && num[low] == num[low + 1]) low++;
while(high > 0 && num[high] == num[high - 1]) high--;
low++;
high--;
} else if (a+b+c > target) {
} else if (a + b + c > target) {
//skip the duplication
while(high>0 && num[high]==num[high-1]) high--;
while(high > 0 && num[high] == num[high - 1]) high--;
high--;
} else{
} else {
//skip the duplication
while(low<n && num[low]==num[low+1]) low++;
while(low < n && num[low] == num[low + 1]) low++;
low++;
}
}
Expand All @@ -100,9 +101,9 @@ vector<vector<int> > threeSum(vector<int> num, int target) {

int printMatrix(vector< vector<int> > &vv)
{
for(int i=0; i<vv.size(); i++) {
for(int i = 0; i < vv.size(); i++) {
cout << "[";
for(int j=0; j<vv[i].size(); j++) {
for(int j = 0; j < vv[i].size(); j++) {
cout << " " << vv[i][j];
}
cout << "]" << endl;;
Expand All @@ -112,14 +113,14 @@ int printMatrix(vector< vector<int> > &vv)

int main()
{
int a[] = {1,0,-1,0,-2,2};
int a[] = { 1, 0, -1, 0, -2, 2 };
vector<int> n(a, a+6);
int t = 0;
vector< vector<int> > v = fourSum(n, t);
printMatrix(v);

n.clear();
int b[] = {-1,-5,-5,-3,2,5,0,4};
int b[] = { -1, -5, -5, -3, 2, 5, 0, 4 };
n.insert(n.begin(), b, b+8);
t = -7;
v = fourSum(n, t);
Expand Down

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