N-th Tribonacci Number LeetCode solution in C++

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class Solution {
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 public:
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  int tribonacci(int n) {
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    if (n < 2) return n;
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    int prev3 = 0;
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    int prev2 = 1;
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    int prev1 = 1;
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    for (int i = 3; i <= n; i++) {
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      int ans = prev1 + prev2 + prev3;
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      prev3 = prev2;
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      prev2 = prev1;
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      prev1 = ans;
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    }
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    return prev1;
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  }
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};