Adding easy puzzles

puzzles/easy/horse-racing-duals.cpp

@@ -0,0 +1,100 @@
+// https://www.codingame.com/ide/puzzle/horse-racing-duals
+// Xavier Morel - 2016-03-12
+
+#include <iostream>
+#include <string>
+#include <vector>
+#include <algorithm>
+
+using namespace std;
+
+bool two_equals = false;
+
+typedef struct elem_s {
+    int pow;
+    struct elem_s *p;
+    struct elem_s *n;
+} elem;
+
+elem *create_elem(int pw)
+{
+    elem *cur = new elem();
+    cur->p = 0;
+    cur->n = 0;
+    cur->pow = pw;
+    return cur;
+}
+
+elem *add_elem(elem *first, int pw)
+{
+    if (!first) {
+        return create_elem(pw);
+    }
+
+    elem *prev;
+    for (elem *tmp = first; tmp; tmp = tmp->n) {
+        if (pw == tmp->pow) {
+            two_equals = true;
+            return first;
+        } else if (pw < tmp->pow) {
+            elem *cur = create_elem(pw);
+            if (tmp->p) {
+                tmp->p->n = cur;
+            } else {
+                first = cur;
+            }
+            cur->p = tmp->p;
+            cur->n = tmp;
+            tmp->p = cur;
+            return first;
+        }
+        prev = tmp;
+    }
+
+    elem *cur = create_elem(pw);
+    prev->n = cur;
+    cur->p = prev;
+
+    return first;
+}
+
+int main()
+{
+    int N;
+    cin >> N; cin.ignore();
+
+    elem *first = 0;
+    elem *cur;
+
+    for (int i = 0; i < N; i++) {
+        int pw;
+        cin >> pw; cin.ignore();
+        first = add_elem(first, pw);
+    }
+
+    if (two_equals) {
+        cout << "0" << endl;
+    } else {
+        int least = -1;
+        elem *prev = 0;
+        for (elem *tmp = first; tmp; tmp = tmp->n) {
+            if (prev) {
+                delete prev;
+            }
+            if (tmp->n) {
+                int diff = tmp->n->pow - tmp->pow;
+                if (least == -1 || least > diff) {
+                    least = diff;
+                }
+            }
+            prev = tmp;
+        }
+        if (prev) {
+            delete prev;
+        }
+        if (least < 0) {
+            least = 0;
+        }
+        cout << least << endl;
+    }
+}