Find unique triplets in an array div-bargali#806

Find unique triplets in an array div-bargali#806

Author: div-bargali

C++/Data-Structures/Array/threeSum.cpp

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+/*
+ Given an array nums of n integers, find all unique triplets in the array which gives the sum of zero.
+*/
+#include<bits/stdc++.h>
+using namespace std;
+vector<vector<int>> threeSum(vector<int>& nums) {
+ int n = nums.size();
+ if(n < 3)
+ return {};
+ sort(nums.begin(),nums.end());
+ vector <vector<int>> result;
+ unordered_set<string> triplets;
+ int i = 0;
+ while(i < n -2){
+ int j = i+1, k = n-1;
+ while(j<k){
+ int sum = nums[i] + nums[j] + nums[k];
+ if(sum == 0){
+ string newTriplet = to_string(nums[i]) + ":"
+ + to_string(nums[j]) + ":" 
+ + to_string(nums[k]);
+ if(triplets.find(newTriplet) == triplets.end()){
+ triplets.insert(newTriplet);
+ result.push_back({nums[i],nums[j],nums[k]});
+ }
+ j++;
+ k--;
+ }
+ else if(sum > 0)
+ k--;
+ else if(sum < 0)
+ j++;
+ }
+ i++;
+ } 
+ return result;
+}
+
+int main(){
+ int n;
+ vector <int> nums;
+ cin>>n;
+ for(int i = 0; i < n; i++){
+ int input;
+ cin>>input;
+ nums.push_back(input);
+ }
+ vector <vector<int>> result = threeSum(nums);
+ for(int i = 0; i< result.size(); i++){
+ for(int j = 0; j< result[0].size(); j++)
+ cout<<result[i][j]<<" ";
+ cout<<"\n";
+ }
+}
+//Time complexity: O(n^2), Space complexity: O(n)

Java/Algorithms/Graph-Algorithms/Dijkstra.java

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+import java.util.*;
+import java.lang.*;
+class DijkstraAlgo{
+ static final int V=9;
+ static int minDistance(int dist[], Boolean sptset[]){
+ int min=Integer.MAX_VALUE, min_index=-1;
+ for(int v=0;v<V;v++){
+ if(sptset[v]==false && dist[v]<=min){
+ min=dist[v];
+ min_index=v;
+ }
+ }
+ return min_index;
+ }
+ static void printSolution(int dist[]){
+ System.out.println("Vertex \t\t Distance from Source");
+ for(int v=0;v<V;v++)
+ System.out.println(v+"\t\t"+dist[v]);
+ }
+ static void dijkstra(int graph[][], int src){
+ int dist[]=new int[V];
+ Boolean sptset[]=new Boolean[V];
+
+ dist[src]=0;
+ sptset[src]=false;
+ for(int v=1;v<V;v++){
+ dist[v]=Integer.MAX_VALUE;
+ sptset[v]=false;
+ }
+ for(int count=0;count<V-1;count++){
+ int u=minDistance(dist,sptset);
+ sptset[u]=true;
+ for(int v=0;v<V;v++){
+ if(sptset[v]==false && graph[u][v]!=0 && dist[u]!= Integer.MAX_VALUE && 
+ (dist[u]+ graph[u][v]) < dist[v]
+ )
+ dist[v]=dist[u]+graph[u][v];
+ } 
+ }
+ printSolution(dist);
+ }
+ public static void main(String[] args) {
+ int graph[][]=new int[][]{ 
+ { 0, 4, 0, 0, 0, 0, 0, 8, 0 }, 
+ { 4, 0, 8, 0, 0, 0, 0, 11, 0 }, 
+ { 0, 8, 0, 7, 0, 4, 0, 0, 2 }, 
+ { 0, 0, 7, 0, 9, 14, 0, 0, 0 }, 
+ { 0, 0, 0, 9, 0, 10, 0, 0, 0 }, 
+ { 0, 0, 4, 14, 10, 0, 2, 0, 0 }, 
+ { 0, 0, 0, 0, 0, 2, 0, 1, 6 }, 
+ { 8, 11, 0, 0, 0, 0, 1, 0, 7 }, 
+ { 0, 0, 2, 0, 0, 0, 6, 7, 0 } }; 
+ dijkstra(graph, 0);
+ 
+ }
+}