diff options
Diffstat (limited to 'find_max_non_decr_arr_len.c')
-rw-r--r-- | find_max_non_decr_arr_len.c | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/find_max_non_decr_arr_len.c b/find_max_non_decr_arr_len.c new file mode 100644 index 0000000..0f218b4 --- /dev/null +++ b/find_max_non_decr_arr_len.c @@ -0,0 +1,53 @@ +// 2945. Find Maximum Non-decreasing Array Length +#include "leetcode.h" + +/* + * you are given a 0-indexed integer array 'nums'. you can perform any number of + * operations, where each operation involves selecting a subarray of the array + * and replacing it with the sum of its elements. for example, if the given + * array is '[1, 3, 5, 6]' and you select '[3, 5]', the array will convert to + * '[1, 8, 6]'. return the maximum length of a non-decreasing array that can be + * made after applying the aforementioned operations. a subarray is a contiguous + * non-empty sequence of elements within an array + */ + +struct node { + int px; + int rx; + int ml; +}; + +int findMaximumLength(int *nums, int numsSize) { + struct node *dp = (struct node *)malloc((numsSize + 1) * sizeof(int)); + int dpl = 1, px = 0; + memset(&dp[0], 0, sizeof(struct node)); + for (int i = 1, j = 0; i <= numsSize; ++i) { + px += nums[i - 1]; + if (j >= dpl) + j = dpl - 1; + while (j + 1 < dpl) { + if (!(px >= dp[j + 1].rx + dp[j + 1].px)) + break; + ++j; + } + int ml = dp[j].ml + 1, rx = px - dp[j].px; + while (1) { + if (rx + px >= dp[dpl - 1].rx + dp[dpl - 1].px) + break; + --dpl; + } + dp[dpl].px = px; + dp[dpl].rx = rx; + dp[dpl].ml = ml; + } + int ans = dp[dpl - 1].ml; + free(dp); + return ans; +} + +int main() { + int n1[] = {5, 2, 2}, n2[] = {1, 2, 3, 4}, n3[] = {4, 3, 2, 6}; + printf("%d\n", findMaximumLength(n1, ARRAY_SIZE(n1))); // expect: 1 + printf("%d\n", findMaximumLength(n2, ARRAY_SIZE(n2))); // expect: 4 + printf("%d\n", findMaximumLength(n3, ARRAY_SIZE(n3))); // expect: 3 +} |