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Can some Explain why my solution fails

By hrishabhpatel09, history, 18 months ago, In English

Here is a Problem: 2069B - Set of Strangers Here is Soln: 306760751

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18 months ago, hide # |
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Bro tune third question 2069C - Beautiful Sequence,dp ka implementation kaise kiya hai yeh bata sakta hai , like approach mujhe bhi aagayi thi but i don't know how to implement it

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    18 months ago, hide # ^ |
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    good subsequences are of form 12222....3. count of 2s >= 1 and start me 1 and end me 3.

    // dp[i][1] bolega no of subsequences of form "1" till i // dp[i][2] bolega no of subsequences of form "122...." till i // dp[i][3] bolega no of subsequences of form "12....3" till i

    // dp[i][1] ,agar a[i] == 1, dp[i][1] = 1 + dp[i-1][1], nhi toh base dp[i][1] = dp[i-1][1]

    // dp[i][2], agar a[i] != 2 toh dp[i][2] = dp[i-1][2] // but if a[i] == 2 // i-1 tak jo already 12... bangayi ume 2 jod de, ya mat jod. total 2 * dp[i-1][2] hojayengi // i-1 tak jo no of form "1" ki subsequences hai unme 2 jod de, toh dp[i — 1][1] // so dp[i][2] = dp[i — 1][1] + 2 * dp[i — 1][2]

    //dp[i][3], i-1 tak jo already 12.... bangayi unme 3 jod de bas, dp[i][3] = dp[i-1][2]

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