Algorithm
Problem link- https://www.spoj.com/problems/BUBBLESORT/
BUBBLESORT - Bubble Sort
One of the simplest sorting algorithms, the Bubble Sort, can be expressed as (0-based array):
procedure bubbleSort( A : list of sortable items ) n = length(A) repeat swapped = false for i = 1 to n-1 inclusive do /* if this pair is out of order */ if A[i-1] > A[i] then /* swap them and remember something changed */ swap( A[i-1], A[i] ) swapped = true end if end for until not swapped end procedure
Now, given an array of N integers, you have to find out how many swap opeartions occur if the Bubble Sort algorithm is used to sort the array.
Input
Input begins with a line containing an integer T (1<=T<=100), denoting the number of test cases. Then T test cases follow. Each test case begins with a line containing an integer N (1<=N<=10000), denoting the number of integers in the array, followed by a line containing N space separated 32-bit integers.
Output
For each test case, output a single line in the format Case X: Y, where X denotes the test case number and Y denotes the number of swap operations needed modulo 10000007.
Example
Input: 1 4 3 2 1 4 Output: Case 1: 3
Code Examples
#1 Code Example with C++ Programming
Code -
C++ Programming
#include <bits/stdc++.h7gt;
#include <limits.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef vector<int> vi;
#define MOD (ll)10000007
#define pb push_back
#define EPS 1e-9
#define FOR(i, n) for(int i = 0;i < n; i++)
#define pi(a) printf("%d\n", a)
#define all(c) c.begin(), c.end()
#define tr(container, it) for(typeof(container.begin()) it = container.begin(); it != container.end(); it++)
#define gc getchar_unlocked
template <typename T> T gcd(T a, T b){return (b==0)?a:gcd(b,a%b);}
template <typename T> T lcm(T a, T b){return a*(b/gcd(a,b));}
template <typename T> T mod_exp(T b, T p, T m){T x = 1;while(p){if(p&1)x=(x*b)%m;b=(b*b)%m;p=p>>1;}return x;}
template <typename T> T invFermat(T a, T p){return mod_exp(a, p-2, p);}
template <typename T> T exp(T b, T p){T x = 1;while(p){if(p&1)x=(x*b);b=(b*b);p=p>>1;}return x;}
void si(int &x){
register int c = gc();
x = 0;
int neg = 0;
for(;((c<48 || c>57) && c != '-');c = gc());
if(c=='-') {neg=1;c=gc();}
for(;c>47 && c<58;c = gc()) {x = (x<<1) + (x<<3) + c - 48;}
if(neg) x=-x;
}
int n;
int mergeTwo(int left[], int right[], int leftSize, int rightSize, int arr[]){
int i = 0, j = 0, k = 0;
int count = 0;
while(i < leftSize && j < rightSize){
if(left[i] > right[j]){
arr[k] = right[j];
j++;
count = (count + leftSize-i)%MOD;
}else if(right[j] >= left[i]){
arr[k] = left[i];
i++;
}
k++;
}
while(i < leftSize){
arr[k] = left[i];
i++;
k++;
}
while(j < rightSize){
arr[k] = right[j];
j++;
k++;
}
return count;
}
int inversionCount(int arr[], int size){
if(size <= 1)
return 0;
int leftSize = size/2;
int rightSize = size-leftSize;
int left[leftSize];
for(int i = 0;i < leftSize; i++){
left[i] = arr[i];
// cout<<left[i]<<endl;
}
// cout<<"HELLO"<<endl;
int right[rightSize];
for(int i = 0;i < rightSize; i++){
right[i] = arr[i+leftSize];
}
int count = 0;
count = (count + inversionCount(left, leftSize))%MOD;
count = (count + inversionCount(right, rightSize))%MOD;
count = (count + mergeTwo(left, right, leftSize, rightSize, arr))%MOD;
return count;
}
int main(){
int t;
si(t);
int kase = 1;
while(t--){
si(n);
int arr[n];
FOR(i, n) si(arr[i]);
ll ans = inversionCount(arr, n);
printf("Case %d: %lld\n", kase, ans);
kase++;
}
return 0;
}
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Input
4
3 2 1 4
Output
Demonstration
SPOJ Solution-Bubble Sort-Solution in C, C++, Java, Python