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-rw-r--r--reverse_subarr_max_arr_val.c29
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+// 1330. Reverse Subarray To Maximize Array Value
+#include "leetcode.h"
+
+/*
+ * given an intger array 'nums'. the value of this array is defined as the sum
+ * of '| nums[i] - nums[i + 1] |' for all '0 <= i < nums.len - 1'. you are
+ * allowed to select any subarray of the given array and reverse it. you can
+ * perform this operation only once. find maximum possible value of the final
+ * array.
+ */
+
+int maxValueAfterReverse(int *nums, int numsSize) {
+ int total = 0, sum = 0, min2 = 123456, max2 = -123456, n = numsSize;
+ for (int i = 0; i < n - 1; ++i) {
+ int a = nums[i], b = nums[i + 1];
+ total += abs(a - b);
+ sum = fmax(sum, abs(nums[0] - b) - abs(a - b));
+ sum = fmax(sum, abs(nums[n - 1] - a) - abs(a - b));
+ min2 = fmin(min2, fmax(a, b));
+ max2 = fmax(max2, fmin(a, b));
+ }
+ return total + fmax(sum, (max2 - min2) * 2);
+}
+
+int main() {
+ int n1[] = {2, 3, 1, 5, 4}, n2[] = {2, 4, 9, 24, 2, 1, 10};
+ printf("%d\n", maxValueAfterReverse(n1, ARRAY_SIZE(n1))); // expect: 10
+ printf("%d\n", maxValueAfterReverse(n2, ARRAY_SIZE(n2))); // expect: 68
+}