feat: add ternary search on integers implementation

Author: LuchoBazz

searches/searches_ternary_search_on_integers_I.cpp

@@ -0,0 +1,21 @@
+int64_t ternary_search(const function<int64_t(int64_t)> &func, int64_t low,
+                       int64_t high) {
+
+    while (high - low > 2) {
+        int64_t delta = (high - low) / 3LL;
+        int64_t m1 = low + delta, m2 = high - delta;
+
+        if (func(m1) > func(m2)) { // change to < to find the maximum
+            low = m1;
+        } else {
+            high = m2;
+        }
+    }
+    int64_t best = NEUTRO;
+    for (int64_t mid = low; mid <= high; ++mid) {
+        best = min(best, func(mid));
+    }
+    return best;
+}
+// Usage:
+// int64_t best = ternary_search(funct, low, high);