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authorJack Sangdahl <[email protected]>2025-09-25 21:03:37 -0600
committerJack Sangdahl <[email protected]>2025-09-25 21:03:37 -0600
commit23353c144ac9b158af7616dc46b636d53b73ce34 (patch)
tree3394d416aa99e9dc1c84cc07e663e6cc3d844570
parentafadd0bbf56f8aff8c5b397df08731c750302fd4 (diff)
downloadleetcode-23353c144ac9b158af7616dc46b636d53b73ce34.tar.gz
leetcode-23353c144ac9b158af7616dc46b636d53b73ce34.zip
611. valid triangle number
-rw-r--r--valid_triangle_number.c31
-rw-r--r--valid_triangle_number.py31
2 files changed, 62 insertions, 0 deletions
diff --git a/valid_triangle_number.c b/valid_triangle_number.c
new file mode 100644
index 0000000..83585f7
--- /dev/null
+++ b/valid_triangle_number.c
@@ -0,0 +1,31 @@
+// 611. Valid Triangle Number
+#include "leetcode.h"
+
+/*
+ * given an integer array 'nums', return the number of triplets chosen from the
+ * array that can make triangles if we take them as side lengths of a triangle
+ */
+
+int cmp(const void *a, const void *b) { return (*(int *)a - *(int *)b); }
+
+int triangleNumber(int *nums, int numsSize) {
+ qsort(nums, numsSize, sizeof(int), cmp);
+ int ans = 0;
+ for (int k = 2; k < numsSize; ++k) {
+ int i = 0, j = k - 1;
+ while (i < j) {
+ if (nums[i] + nums[j] > nums[k]) {
+ ans += j - i;
+ j--;
+ } else
+ i++;
+ }
+ }
+ return ans;
+}
+
+int main() {
+ int n1[] = {2, 2, 3, 4}, n2[] = {4, 2, 3, 4};
+ printf("%d\n", triangleNumber(n1, ARRAY_SIZE(n1))); // expect: 3
+ printf("%d\n", triangleNumber(n2, ARRAY_SIZE(n2))); // expect: 4
+}
diff --git a/valid_triangle_number.py b/valid_triangle_number.py
new file mode 100644
index 0000000..8460292
--- /dev/null
+++ b/valid_triangle_number.py
@@ -0,0 +1,31 @@
+# 611. Valid Triangle Number
+
+"""
+given an integer array 'nums', return the number of triplets chosen from the
+array that can make triangles if we take them as side lengths of a triangle
+"""
+
+
+class Solution(object):
+ def triangleNumber(self, nums):
+ """
+ :type nums: List[int]
+ :rtype: int
+ """
+ nums.sort()
+ n, ans = len(nums), 0
+ for k in range(2, n):
+ i, j = 0, k - 1
+ while i < j:
+ if nums[i] + nums[j] > nums[k]:
+ ans += j - i
+ j -= 1
+ else:
+ i += 1
+ return ans
+
+
+if __name__ == "__main__":
+ obj = Solution()
+ print(obj.triangleNumber(nums=[2, 2, 3, 4]))
+ print(obj.triangleNumber(nums=[4, 2, 3, 4]))