leetcode

commit ff3ff0b5c5ac73e356ffbf46724bdf28f6210f7b
parent c151ea288ff0e52214030607a7a4c30c71193cd2
Author: Jack Sangdahl <jack@pngu.org>
Date:   Wed, 17 Jun 2026 10:00:32 -0600

3614. process string with special operations 2

Diffstat:
A
process_str_special_op2.c
 | 
66
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A
process_str_special_op2.py
 | 
50
++++++++++++++++++++++++++++++++++++++++++++++++++

2 files changed, 116 insertions(+), 0 deletions(-)
diff --git a/process_str_special_op2.c b/process_str_special_op2.c
@@ -0,0 +1,66 @@
+// 3614. Process String with Special Operations II
+#include "leetcode.h"
+
+/*
+ * you are given a string 's' consisting of lowercase english letters and the
+ * special characters '*', '#', and '%'. you are also given an integer 'k'.
+ * build a new string 'result' by processing 's' according to the following
+ * rules from left to right: if the letter is a lowercase english letter append
+ * it to 'result'. a '*' removes the last character from 'result'. a '#'
+ * duplicates the current 'result' and appends it to itself. a '%' reverses the
+ * current 'result'. return the k'th character of the final string 'result'. if
+ * 'k' is out of the bounds of 'result', return '.'.
+ */
+
+char processStr(char *s, long long k) {
+  long long l = 0, p = k;
+  for (int i = 0; s[i] != '\0'; i++) {
+    char c = s[i];
+    if (c == '*') {
+      if (l > 0)
+        l--;
+    } else if (c == '#')
+      l *= 2;
+    else if (c == '%')
+      continue;
+    else
+      l++;
+  }
+  if (k >= l)
+    return '.';
+  int n = 0;
+  while (s[n] != '\0')
+    n++;
+  for (int i = n - 1; i >= 0; i--) {
+    char c = s[i];
+    if (c == '*')
+      l++;
+    else if (c == '#') {
+      if (p >= l / 2)
+        p -= l / 2;
+      l /= 2;
+    } else if (c == '%')
+      p = l - 1 - p;
+    else {
+      if (l == p + 1)
+        return c;
+      l--;
+    }
+  }
+  return '.';
+}
+
+int main() {
+  char *s1 = "a#b%*";
+  char *s2 = "cd%#*#";
+  char *s3 = "z*#";
+  char r1 = processStr(s1, 1);
+  char r2 = processStr(s2, 3);
+  char r3 = processStr(s3, 0);
+  printf("%c\n", r1);
+  assert(r1 == 'a');
+  printf("%c\n", r2);
+  assert(r2 == 'd');
+  printf("%c\n", r3);
+  assert(r3 == '.');
+}
diff --git a/process_str_special_op2.py b/process_str_special_op2.py
@@ -0,0 +1,50 @@
+# 3614. Process String with Special Operations II
+
+"""
+you are given a string 's' consisting of lowercase english letters and the
+special characters '*', '#', and '%'. you are also given an integer 'k'.
+build a new string 'result' by processing 's' according to the following
+rules from left to right: if the letter is a lowercase english letter append
+it to 'result'. a '*' removes the last character from 'result'. a '#'
+duplicates the current 'result' and appends it to itself. a '%' reverses the
+current 'result'. return the k'th character of the final string 'result'. if
+'k' is out of the bounds of 'result', return '.'.
+"""
+
+
+class Solution:
+    def processStr(self, s: str, k: int) -> str:
+        l, p = 0, k
+        for c in s:
+            if c == "*":
+                if l > 0:
+                    l -= 1
+            elif c == "#":
+                l *= 2
+            elif c == "%":
+                pass
+            else:
+                l += 1
+        if k >= l:
+            return "."
+        for c in s[::-1]:
+            if c == "*":
+                l += 1
+            elif c == "#":
+                if p >= l // 2:
+                    p -= l // 2
+                l = l // 2
+            elif c == "%":
+                p = (l - 1) - p
+            else:
+                if l == p + 1:
+                    return c
+                l -= 1
+        return s[p]
+
+
+if __name__ == "__main__":
+    obj = Solution()
+    print(obj.processStr(s="a#b%*", k=1))
+    print(obj.processStr(s="cd%#*#", k=3))
+    print(obj.processStr(s="z*#", k=0))