diff options
Diffstat (limited to 'math/inversionsMerge.cpp')
| -rw-r--r-- | math/inversionsMerge.cpp | 27 |
1 files changed, 0 insertions, 27 deletions
diff --git a/math/inversionsMerge.cpp b/math/inversionsMerge.cpp deleted file mode 100644 index 8235b11..0000000 --- a/math/inversionsMerge.cpp +++ /dev/null @@ -1,27 +0,0 @@ -// Laufzeit: O(n*log(n)) -ll merge(vector<ll>& v, vector<ll>& left, vector<ll>& right) { - int a = 0, b = 0, i = 0; - ll inv = 0; - while (a < sz(left) && b < sz(right)) { - if (left[a] < right[b]) v[i++] = left[a++]; - else { - inv += sz(left) - a; - v[i++] = right[b++]; - } - } - while (a < sz(left)) v[i++] = left[a++]; - while (b < sz(right)) v[i++] = right[b++]; - return inv; -} - -ll mergeSort(vector<ll> &v) { // Sortiert v und gibt Inversionszahl zurück. - int n = sz(v); - vector<ll> left(n / 2), right((n + 1) / 2); - for (int i = 0; i < n / 2; i++) left[i] = v[i]; - for (int i = n / 2; i < n; i++) right[i - n / 2] = v[i]; - - ll result = 0; - if (sz(left) > 1) result += mergeSort(left); - if (sz(right) > 1) result += mergeSort(right); - return result + merge(v, left, right); -} |