.

Day6Problem1.cpp

@@ -0,0 +1,51 @@
+#include <cstdio>
+#include <cstring>
+#include <string>
+#include <cmath>
+#include <cstdlib>
+#include <cassert>
+#include <iostream>
+#include <vector>
+#include <algorithm>
+using namespace std;
+// Sort and compare.
+// Do as you are told.
+int main()
+{
+    int n;
+    int arr[100000];
+    scanf("%d",&n);
+    for (int i=0;i<n;i++)
+        scanf("%d",&arr[i]);
+
+    int sorted[100000];
+    for (int i=0;i<n;i++)
+        sorted[i]=arr[i];
+    sort(sorted,sorted+n);
+    vector<int> diff;
+    for (int i=0;i<n;i++)
+        if (sorted[i]!=arr[i])
+            diff.push_back(i);
+    if (diff.size()==0)
+        printf("yes\n");  
+    else if (diff.size()==2)
+        printf("yes\nswap %d %d\n",diff[0]+1,diff[1]+1); //Index starts at 1!!!
+    else //Let's try reverse it!
+    {
+        int st = diff[0], ed = diff[diff.size()-1];
+        while (st<ed)
+        {
+            swap(arr[st],arr[ed]);
+            st++;
+            ed--;
+        }
+        int flag=1;
+        for (int i=0;i<n;i++)
+            if (sorted[i]!=arr[i])
+            {
+                printf("no\n");  
+                return 0;
+            }
+        printf("yes\nreverse %d %d\n",diff[0]+1,diff[diff.size()-1]+1); //Index starts at 1!!!
+    }
+}

Day6Problem2.cpp

@@ -0,0 +1,30 @@
+#include <math.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <limits.h>
+#include <stdbool.h>
+
+int main(){
+    int n,c_i,count=0; 
+    scanf("%d",&n);
+    int *c = malloc(sizeof(int) * n);
+    for(c_i = 0; c_i < n-1; c_i++){
+       scanf("%d",&c[c_i]);
+    }
+    for(c_i = 0; c_i < n-1; c_i++)
+        {
+        if(c[(c_i)+2]==0)
+            {
+            c_i++;
+            count++;
+        }
+            else if(c[(c_i)+1]==0)
+                {
+                count++;
+            }
+        }
+    printf("%d",count);
+    return 0;
+}

Day6Problem3.cpp

@@ -0,0 +1,33 @@
+#include <cstdio>
+#include <cstring>
+#include <string>
+#include <cmath>
+#include <cstdlib>
+#include <map>
+#include <iostream>
+#include <vector>
+#include <algorithm>
+using namespace std;
+
+int main() {
+    int t;
+    scanf("%d",&t);
+    while (t--)
+    {
+        int n;
+        int arr[1000];
+        scanf("%d",&n);
+        for (int i=0;i<n;i++)
+            scanf("%d",&arr[i]);
+        int inv = 0;
+        for (int i=0;i<n;i++)
+            for (int j=i+1;j<n;j++)
+                if (arr[i] > arr[j])
+                    inv ++;
+        if (inv%2==0)
+            printf("YES\n");
+        else
+            printf("NO\n");
+    }
+    return 0;
+}

Day6Problem4.cpp

@@ -0,0 +1,62 @@
+#include <cmath>
+#include <cstdio>
+#include <vector>
+#include <iostream>
+#include <algorithm>
+using namespace std;
+
+// Main algorithm: in order to rotate the whole matrix, we'll just rotate one ring at a time
+// We can do this in-place to achieve O(1) additional space complexity
+int main() {
+    int M, N, R;
+    cin>>M>>N>>R;
+    int **matrix = new int*[M];
+    for(int i = 0; i < M; i++) {
+        matrix[i] = new int[N];
+        for(int j = 0; j < N; j++) {
+            cin>>matrix[i][j];
+        }
+    }
+
+    int numRings = min(M,N)/2;
+    for(int i = 0; i < numRings; i++) {
+        // Subtract the number of 360 degree rotations from R
+        // A 360 degree rotation = rotating the same number of times as the perimeter of the current ring
+        int numRotations = R%(2*(M + N - 4*i) - 4);
+        for(int rotation = 0; rotation < numRotations; rotation++) {
+            // Rotate the ring (see the clockwise algorithm for an in-depth example of how this is done)
+            // Rotate top row
+            for(int j = i; j < N-i-1; j++) {
+                int tmp = matrix[i][j];
+                matrix[i][j] = matrix[i][j+1];
+                matrix[i][j+1] = tmp;
+            }
+            // Rotate right column
+            for(int j = i; j < M-i-1; j++) {
+                int tmp = matrix[j][N-i-1];
+                matrix[j][N-i-1] = matrix[j+1][N-i-1];
+                matrix[j+1][N-i-1] = tmp;
+            }
+            // Rotate bottom row
+            for(int j = N-i-1; j > i; j--) {
+                int tmp = matrix[M-i-1][j];
+                matrix[M-i-1][j] = matrix[M-i-1][j-1];
+                matrix[M-i-1][j-1] = tmp;
+            }
+            // Rotate left column
+            for(int j = M-i-1; j > i+1; j--) {
+                int tmp = matrix[j][i];
+                matrix[j][i] = matrix[j-1][i];
+                matrix[j-1][i] = tmp;
+            }
+        }
+    }
+    // Output final matrix
+    for(int i = 0; i < M; i++) {
+        for(int j = 0; j < N; j++) {
+            cout<<matrix[i][j]<<" ";
+        }
+        cout<<"\n";
+    }
+    return 0;
+}

Day6Problem5.py

@@ -0,0 +1,8 @@
+from collections import Counter, OrderedDict
+class OrderedCounter(Counter, OrderedDict):
+    pass
+d = OrderedCounter(input() for _ in range(int(input())))
+print(len(d))
+print(*d.values())
+
+

Raghavtroublemaker/Day5Problem1.java

@@ -0,0 +1,23 @@
+package com.samuelale.practice;
+import java.math.BigInteger;
+import java.util.Scanner;
+
+
+public class FibonacciMod {
+
+    public static void main(String[] args) {
+        Scanner s = new Scanner(System.in);
+        BigInteger t1 = s.nextBigInteger();
+        BigInteger t2 = s.nextBigInteger();
+        BigInteger n = s.nextBigInteger();
+
+        BigInteger ti = new BigInteger("0");
+        for(int i=3; i<=n.intValue(); i++) {
+            ti = t1.add(t2.pow(2));
+            t1 = t2;
+            t2 = ti;
+        }
+        System.out.println(ti);
+    }
+
+}

Raghavtroublemaker/Day5Problem2.java

@@ -0,0 +1,71 @@
+package com.samuelale.practice;
+
+import java.util.;
+
+
+public class CutTheTree {
+
+    private static class Node {
+        int value;
+        int total;
+        List<Node> edges;
+
+        Node(int val) {
+            this.value = val;
+            total = 0;
+            edges = new ArrayList<>();
+        }
+
+        @Override
+        public String toString() {
+            return "Val: " + value + " | Total: " + total; //+ " | Edges: " + edges.toString();
+        }
+    }
+
+    private static HashSet<Node> visited = new HashSet<>();
+
+    private static void findTotal(Node n) {
+        visited.add(n);
+        if(n.edges.isEmpty()) {
+            n.total = n.value;
+        } else {
+            int total = n.value;
+            for(Node edge : n.edges) {
+                if(visited.contains(edge)) continue;
+                visited.add(edge);
+                findTotal(edge);
+                total+=edge.total;
+            }
+            n.total = total;
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner input = new Scanner(System.in);
+        int N = input.nextInt();
+
+        Node[] nodeArr = new Node[N];
+        for(int i=0; i<N; i++) {
+            nodeArr[i] = new Node(input.nextInt());
+        }
+
+        for(int i=0; i<N-1; i++) {
+            int n1 = input.nextInt()-1;
+            int n2 = input.nextInt()-1;
+            nodeArr[n1].edges.add(nodeArr[n2]);
+            nodeArr[n2].edges.add(nodeArr[n1]);
+        }
+
+        // calculate the totals at each node
+        findTotal(nodeArr[0]);
+
+        int minDiff = Integer.MAX_VALUE;
+        for(int i=1; i<N; i++) {
+            int diff = Math.abs(nodeArr[0].total - nodeArr[i].total2);
+            if(diff < minDiff) {
+                minDiff = diff;
+            }
+        }
+        System.out.print(minDiff);
+    }
+}

Raghavtroublemaker/Day5Problem3.java

@@ -0,0 +1,28 @@
+package com.samuelale.practice;
+
+import java.util.HashSet;
+import java.util.Scanner;
+
+
+public class AlgSearchPairs {
+
+    public static void main(String[] args) {
+        Scanner s = new Scanner(System.in);
+        int N = s.nextInt();
+        int K = s.nextInt();
+        HashSet<Integer> valSet = new HashSet<>();
+        for (int i=0; i<N; i++) {
+            valSet.add(s.nextInt());
+        }
+
+        HashSet<Integer> modSet = new HashSet<>(valSet);
+        int pairs = 0;
+        for(int val : valSet) {
+            if(modSet.contains(val+K) || modSet.contains(val-K)) {
+                pairs++;
+            }
+            modSet.remove(val);
+        }
+        System.out.print(pairs);
+    }
+}

Raghavtroublemaker/Day5Problem4.java

@@ -0,0 +1,25 @@
+public class ANewHope {
+
+    /*
+     * The strategy will be to create a new week and try to swap shirt values to
+     * look more like the last week until the conditions are met, or we until
+     * we can no longer move shirts around without violating the conditions.
+     */
+    public int count(int[] firstWeek, int[] lastWeek, int D) {
+        int N = firstWeek.length;
+
+        boolean same = true;
+        for(int i=0; i<N; i++) same &= firstWeek[i] == lastWeek[i];
+        if(same) return 1;
+
+        int gap = N-D;
+
+
+        return gap;
+    }
+
+    public static void main(String[] args) {
+        ANewHope hope = new ANewHope();
+        System.out.println(hope.count(new int[]{1,2,3,4}, new int[]{4,3,2,1}, 3));
+    }
+}