Enhance walk function with optimized logic

Refactor walk function to improve performance and clarity.

Author: lrvideckis

library/data_structures_[l,r]/seg_tree_uncommon/walk.hpp

@@ -1,10 +1,22 @@
+int go(int l, int r) {
+//return __lg(min(l & -l, r - l + 1));
+//return __lg(min((l + n) & -(l + n), r - l + 1));
+  return min(__builtin_ctz(l + n), __lg(r - l + 1));
+}
 int walk(int l, int r, const auto& f) {
+  /*
   for (l += n, r += n; l <= r;)
     if (int u = nxt(l, r); f(s[u])) {
       while (u < n)
         if (f(s[2 * u])) u *= 2;
         else (u *= 2)++;
       return u - n;
     }
+  */
+  while (l <= r) {
+    int u = l + n, x = __lg(min(u & -u, r - l + 1));
+    if (f(s[u >> x])) r = l + (1 << x) - 1;
+    else l += 1 << x;
+  }
   return -1;
 }