{ "data": { "question": { "questionId": "1042", "questionFrontendId": "1000", "boundTopicId": null, "title": "Minimum Cost to Merge Stones", "titleSlug": "minimum-cost-to-merge-stones", "content": "

There are n piles of stones arranged in a row. The ith pile has stones[i] stones.

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A move consists of merging exactly k consecutive piles into one pile, and the cost of this move is equal to the total number of stones in these k piles.

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Return the minimum cost to merge all piles of stones into one pile. If it is impossible, return -1.

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Example 1:

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\nInput: stones = [3,2,4,1], k = 2\nOutput: 20\nExplanation: We start with [3, 2, 4, 1].\nWe merge [3, 2] for a cost of 5, and we are left with [5, 4, 1].\nWe merge [4, 1] for a cost of 5, and we are left with [5, 5].\nWe merge [5, 5] for a cost of 10, and we are left with [10].\nThe total cost was 20, and this is the minimum possible.\n
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Example 2:

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\nInput: stones = [3,2,4,1], k = 3\nOutput: -1\nExplanation: After any merge operation, there are 2 piles left, and we can't merge anymore.  So the task is impossible.\n
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Example 3:

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\nInput: stones = [3,5,1,2,6], k = 3\nOutput: 25\nExplanation: We start with [3, 5, 1, 2, 6].\nWe merge [5, 1, 2] for a cost of 8, and we are left with [3, 8, 6].\nWe merge [3, 8, 6] for a cost of 17, and we are left with [17].\nThe total cost was 25, and this is the minimum possible.\n
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Constraints:

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