C++ implementation of Josephus problem (#913)

Author: KunalKartik02

algorithms/C++/JosephusProblem/josephus_problem.cpp

@@ -0,0 +1,52 @@
+// Problem statement - Consider a game where there are n children(numbered 1,
+// 2,…, n) in a circle.During the game, every second child is removed from the
+// circle, until there are no children left.In which order will the children be
+// removed?
+
+// problem link - https://cses.fi/problemset/task/2162/
+
+#include <bits/stdc++.h>
+#define ll long long
+using namespace std;
+
+void solve() {
+    ll n;
+    cin >> n;
+    set<ll> s;
+    for (int i = 1; i <= n; i++) s.insert(i);
+    auto it = s.begin();
+    ll c = 0;
+    ll cnt = n;
+    while (cnt != 1) {
+        --cnt;
+        if (c < 1) {
+            ++c;
+            ++it;
+        }
+        if (it == s.end())
+            it = s.begin();
+        if (c) {
+            cout << *it << " ";
+
+            s.erase(it++);
+            if (it == s.end())
+                it = s.begin();
+            c = 0;
+            if (it == s.end())
+                it = s.begin();
+        }
+    }
+    cout << *s.begin() << endl;
+}
+//----------------------Main----------------------------//
+
+int main() {
+    FIO;
+
+    // test case - 7
+    // output - 2 4 6 1 5 3 7
+
+    solve();
+
+    return 0;
+}