leetcode

commit 7187348d45fa427319707488e5affe5d5b97f708
parent 0bc0cb90d1af8a72f45dfe7fe93025c368a2790d
Author: Jack Sangdahl <jack@pngu.org>
Date:   Wed,  9 Oct 2024 22:02:23 -0600

962. maximum width ramp

Diffstat:
A
maximum_width_ramp.c
 | 
33
+++++++++++++++++++++++++++++++++
A
maximum_width_ramp.py
 | 
30
++++++++++++++++++++++++++++++

2 files changed, 63 insertions(+), 0 deletions(-)
diff --git a/maximum_width_ramp.c b/maximum_width_ramp.c
@@ -0,0 +1,33 @@
+// 962. Maximum Width Ramp
+#include "leetcode.h"
+
+/*
+ * a ramp in an integer array 'nums' is a pair '(i, j)' for which 'i < j' and
+ * 'nums[i] <= nums[j]'. the width of such ramp is 'j - i'. given an integer
+ * array 'nums', return the maximum width of a ramp in 'nums' if there is no
+ * ramp in 'nums', return 0
+ */
+
+int maxWidthRamp(int *nums, int numsSize) {
+  int ans = 0, idx = 0;
+  int *stack = (int *)malloc(numsSize * sizeof(int));
+  for (int i = 0; i < numsSize; i++) {
+    if (!idx)
+      stack[idx++] = i;
+    else {
+      if (nums[i] <= nums[stack[idx - 1]])
+        stack[idx++] = i;
+    }
+  }
+  for (int i = numsSize - 1; i >= 0; i--)
+    while (idx && nums[i] >= nums[stack[idx - 1]])
+      ans = fmax(ans, i - stack[--idx]);
+  free(stack);
+  return ans;
+}
+
+int main() {
+  int n1[] = {6, 0, 8, 2, 1, 5}, n2[] = {9, 8, 1, 0, 1, 9, 4, 0, 4, 1};
+  printf("%d\n", maxWidthRamp(n1, ARRAY_SIZE(n1))); // expect: 4
+  printf("%d\n", maxWidthRamp(n2, ARRAY_SIZE(n2))); // expect: 7
+}
diff --git a/maximum_width_ramp.py b/maximum_width_ramp.py
@@ -0,0 +1,30 @@
+# 962. Maximum Width Ramp
+
+"""
+a ramp in an integer array 'nums' is a pair '(i, j)' for which 'i < j' and
+'nums[i] <= nums[j]'. the width of such ramp is 'j - i'. given an integer
+array 'nums', return the maximum width of a ramp in 'nums' if there is no
+ramp in 'nums', return 0
+"""
+
+
+class Solution(object):
+    def maxWidthRamp(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        stack, ans = [], 0
+        for i, j in enumerate(nums):
+            if not stack or nums[stack[-1]] > j:
+                stack.append(i)
+        for i in range(len(nums))[::-1]:
+            while stack and nums[stack[-1]] <= nums[i]:
+                ans = max(ans, i - stack.pop())
+        return ans
+
+
+if __name__ == "__main__":
+    obj = Solution()
+    print(obj.maxWidthRamp(nums=[6, 0, 8, 2, 1, 5]))
+    print(obj.maxWidthRamp(nums=[9, 8, 1, 0, 1, 9, 4, 0, 4, 1]))