leetcode

commit 785e23460e5e020b75b806f6a3d44ba5c870293a
parent 83b9b76710d7b75eb1ddb8d93996b16604f4517c
Author: Jack Sangdahl <jack@pngu.org>
Date:   Thu, 16 Apr 2026 20:59:04 -0600

3761. minimum absolute distance between mirror pairs

Diffstat:
A
min_abs_dist_mirror_pair.c
 | 
99
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A
min_abs_dist_mirror_pair.py
 | 
27
+++++++++++++++++++++++++++

2 files changed, 126 insertions(+), 0 deletions(-)
diff --git a/min_abs_dist_mirror_pair.c b/min_abs_dist_mirror_pair.c
@@ -0,0 +1,99 @@
+// 3761. Minimum Absolute Distance Between Mirror Pairs
+#include "leetcode.h"
+
+/*
+ * you are given an integer array 'nums'. a mirror pair is a pair of indices
+ * '(i, j)' such that '0 <= i < j < nums.length' and 'reverse(nums[i]) ==
+ * nums[j]'. return the minimum absolute distance between the indices of any
+ * mirror pair. the absolute distance between indices is 'i' and 'j' is 'abs(i -
+ * j)'. if no mirror pairs exists, return -1.
+ */
+
+struct hash_item {
+  int key;
+  int val;
+  UT_hash_handle hh;
+};
+
+struct hash_item *hash_find_item(struct hash_item **obj, int key) {
+  struct hash_item *pEntry = NULL;
+  HASH_FIND_INT(*obj, &key, pEntry);
+  return pEntry;
+}
+
+bool hash_add_item(struct hash_item **obj, int key, int val) {
+  if (hash_find_item(obj, key)) {
+    return false;
+  }
+  struct hash_item *pEntry =
+      (struct hash_item *)malloc(sizeof(struct hash_item));
+  pEntry->key = key;
+  pEntry->val = val;
+  HASH_ADD_INT(*obj, key, pEntry);
+  return true;
+}
+
+bool hash_set_item(struct hash_item **obj, int key, int val) {
+  struct hash_item *pEntry = hash_find_item(obj, key);
+  if (!pEntry) {
+    hash_add_item(obj, key, val);
+  } else {
+    pEntry->val = val;
+  }
+  return true;
+}
+
+int hash_get_item(struct hash_item **obj, int key, int defaultVal) {
+  struct hash_item *pEntry = hash_find_item(obj, key);
+  if (!pEntry) {
+    return defaultVal;
+  }
+  return pEntry->val;
+}
+
+void hash_free(struct hash_item **obj) {
+  struct hash_item *curr = NULL, *tmp = NULL;
+  HASH_ITER(hh, *obj, curr, tmp) {
+    HASH_DEL(*obj, curr);
+    free(curr);
+  }
+}
+
+int reverse(int x) {
+  int y = 0;
+  while (x > 0) {
+    y = y * 10 + x % 10;
+    x /= 10;
+  }
+  return y;
+}
+
+int minMirrorPairDistance(int *nums, int numsSize) {
+  struct hash_item *prev = NULL;
+  int ans = numsSize + 1;
+  for (int i = 0; i < numsSize; i++) {
+    int x = nums[i];
+    int prevIndex = hash_get_item(&prev, x, -1);
+    if (prevIndex != -1) {
+      int distance = i - prevIndex;
+      if (distance < ans)
+        ans = distance;
+    }
+    hash_set_item(&prev, reverse(x), i);
+  }
+  hash_free(&prev);
+  return ans == numsSize + 1 ? -1 : ans;
+}
+
+int main() {
+  int n1[] = {12, 21, 45, 33, 54}, n2[] = {120, 21}, n3[] = {21, 120};
+  int r1 = minMirrorPairDistance(n1, ARRAY_SIZE(n1));
+  int r2 = minMirrorPairDistance(n2, ARRAY_SIZE(n2));
+  int r3 = minMirrorPairDistance(n3, ARRAY_SIZE(n3));
+  printf("%d\n", r1);
+  assert(r1 == 1);
+  printf("%d\n", r2);
+  assert(r2 == 1);
+  printf("%d\n", r3);
+  assert(r3 == -1);
+}
diff --git a/min_abs_dist_mirror_pair.py b/min_abs_dist_mirror_pair.py
@@ -0,0 +1,27 @@
+# 3761. Minimum Absolute Distance Between Mirror Pairs
+
+"""
+you are given an integer array 'nums'. a mirror pair is a pair of indices
+'(i, j)' such that '0 <= i < j < nums.length' and 'reverse(nums[i]) ==
+nums[j]'. return the minimum absolute distance between the indices of any
+mirror pair. the absolute distance between indices is 'i' and 'j' is 'abs(i -
+j)'. if no mirror pairs exists, return -1.
+"""
+
+
+class Solution:
+    def minMirrorPairDistance(self, nums: List[int]) -> int:
+        ans = 100000
+        vis = {}
+        for i, j in enumerate(nums):
+            if j in vis:
+                ans = min(ans, i - vis[j])
+            vis[int(str(j)[::-1])] = i
+        return -(ans == 100000) | ans
+
+
+if __name__ == "__main__":
+    obj = Solution()
+    print(obj.minMirrorPairDistance(nums=[12, 21, 45, 33, 54]))
+    print(obj.minMirrorPairDistance(nums=[120, 21]))
+    print(obj.minMirrorPairDistance(nums=[21, 120]))