practice 09-Feb-2020

Author: sureshmangs

algorithms/searching/exponential_search.cpp

@@ -0,0 +1,38 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int exponentialSearch(vector<int> v, int n, int item){
+    int i=1;
+    while(i<n && v[i]<item){
+        i*=2;
+    }
+    int l=i/2, h=i, mid;
+    while(l<=h){
+        mid=(l+h)/2;
+        if(v[mid]==item) return mid;
+        else if(v[mid]>item) h=mid-1;
+        else l=mid+1;
+    }
+    return -1;
+}
+
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    int n;
+    cin>>n;
+    vector<int> v;
+    for(int i=0;i<n;i++){
+        int ch;
+        cin>>ch;
+        v.push_back(ch);
+    }
+    int item;
+    cin>>item;
+    int index=exponentialSearch(v,n,item);
+    if(index>-1) cout<<"Item found at index "<<index;
+    else cout<<"Item not found";
+
+return 0;
+}

algorithms/searching/interpolation_search.cpp

@@ -0,0 +1,34 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int interpolationSearch(vector<int> v, int n, int item){
+    int l=0, h=n-1, pos;
+    while(l<=h){
+        pos= l+((item-v[l])/(v[h]-v[l])*(h-l));
+        if(v[pos]==item) return pos;
+        else if(v[pos]>item) h=pos-1;
+        else l=pos+1;
+    }
+    return -1;
+}
+
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    int n;
+    cin>>n;
+    vector<int> v;
+    for(int i=0;i<n;i++){
+        int ch;
+        cin>>ch;
+        v.push_back(ch);
+    }
+    int item;
+    cin>>item;
+    int index=interpolationSearch(v,n,item);
+    if(index>-1) cout<<"Item found at index "<<index;
+    else cout<<"Item not found";
+
+return 0;
+}

algorithms/searching/jump_search.cpp

@@ -0,0 +1,38 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int jumpSearch(vector<int> v, int n, int item){
+    int m=sqrt(n);
+    for(int i=0;i<n;i+=m){
+        if(v[i]==item) return i;
+        else if(v[i]>item){
+            //Linear search
+            for(int j=i-m;j<i;j++){
+                if(v[j]==item) return j;
+            }
+            return -1;
+        }
+    }
+    return -1;
+}
+
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    int n;
+    cin>>n;
+    vector<int> v;
+    for(int i=0;i<n;i++){
+        int ch;
+        cin>>ch;
+        v.push_back(ch);
+    }
+    int item;
+    cin>>item;
+    int index=jumpSearch(v,n,item);
+    if(index>-1) cout<<"Item found at index "<<index;
+    else cout<<"Item not found";
+
+return 0;
+}

array/juggling_rotation.cpp

@@ -0,0 +1,42 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int gcd(int a, int b){
+    if(b==0) return a;
+    return gcd(b, a%b);
+}
+
+void jugglingRotate(int a[], int n, int d){
+    d%=n;
+    int steps=gcd(n, d);
+    for(int i=0;i<steps;i++){
+        int tmp=a[i];
+        int j=i;
+        while(1){
+            int k=j+d;
+            if(k>=n) k-=n;
+            if(i==k)
+                break;
+            a[j]=a[k];
+            j=k;
+        }
+        a[j]=tmp;
+    }
+    for(int i=0;i<n;i++) cout<<a[i]<<" ";
+}
+
+int main()
+{
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    int n;
+    cin>>n;
+    int a[n];
+    for(int i=0;i<n;i++) cin>>a[i];
+    int d;
+    cin>>d;
+    jugglingRotate(a, n, d);
+
+
+return 0;
+}

array/rotated_search.cpp

@@ -0,0 +1,37 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int searchIt(int a[], int n, int x){
+    int l=0, h=n-1, mid;
+    while(l<=h){
+        mid=l+(h-l)/2;
+        if(a[mid]==x) return mid;
+        else if(a[mid]<a[h]){
+            if(x>a[mid] && x<=a[h]) l=mid+1;
+            else h=mid-1;
+        }
+        else if(a[mid]>a[l]){
+            if(x>=a[l] && x<a[mid]) h=mid-1;
+            else l=mid+1;
+        }
+    }
+    return -1;
+}
+
+int main(){
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    int t;
+    cin>>t;
+    while(t--){
+        int n;
+        cin>>n;
+        int a[n];
+        for(int i=0;i<n;i++) cin>>a[i];
+        int x;
+        cin>>x;
+        cout<<searchIt(a,n,x)<<endl;
+    }
+
+return 0;
+}

array/sorted_rotated_min_search.cpp

@@ -0,0 +1,41 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+int pivot(int a[], int n){
+    int l=0, h=n-1, mid;
+    if(a[l]<=a[h]) return -1;
+    while(l<=h){
+        mid=l+(h-l)/2;
+        if(a[mid]>a[mid+1]) return mid;
+        else if(a[mid]<a[mid-1]) return mid-1;
+        else {
+            if(a[l]<=a[mid]) l=mid+1;
+            else h=mid-1;
+        }
+    }
+}
+
+int minSearch(int a[], int n){
+    int mini=pivot(a,n);
+    mini=(mini+1)%n;
+    return a[mini];
+}
+
+int main(){
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    cout.tie(NULL);
+    int t;
+    cin>>t;
+    while(t--){
+        int n;
+        cin>>n;
+        int a[n];
+        for(int i=0;i<n;i++) cin>>a[i];
+        cout<<minSearch(a,n)<<endl;
+    }
+
+
+
+return 0;
+}

array/sorted_rotated_sum_pair_search.cpp

@@ -0,0 +1,40 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+bool searchIt(int a[], int n, int x){
+    int i;
+    if(n<=1) return false;
+    for(i=0;i<n-1;i++)
+        if(a[i]>a[i+1]) break;
+    int l=(i+1)%n;
+    int h=i;
+    while(l!=h){
+        if(a[l]+a[h]==x) return true;
+        else if(a[l]+a[h]>x){
+            h=(n+h-1)%n;
+        }
+        else {
+            l=(l+n+1)%n;
+        }
+    }
+    return false;
+}
+
+int main(){
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL);
+    int t;
+    cin>>t;
+    while(t--){
+        int n;
+        cin>>n;
+        int a[n];
+        for(int i=0;i<n;i++) cin>>a[i];
+        int x;
+        cin>>x;
+        searchIt(a,n,x)? cout<<"Pair exist" : cout<<"Pair doesn't exist";
+        cout<<endl;
+    }
+
+return 0;
+}