Perfect Squares
Desicription
Given a positive integer n, find the least number of perfect square numbers (for example, 1, 4, 9, 16, …) which sum to n.
Example 1:
1 2 3
| Input: n = 12 Output: 3 Explanation: 12 = 4 + 4 + 4.
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Example 2:
1 2 3
| Input: n = 13 Output: 2 Explanation: 13 = 4 + 9.
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Solution
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
| class Solution { public: int numSquares(int n) { vector<int> dp(n+1, INT_MAX); dp[0] = 0; for(int i = 1, squares; (squares = i * i) <= n; i++) { for(int j = squares; j <= n; j++) { if(dp[j] > dp[j - squares] + 1) { dp[j] = dp[j - squares] + 1; } } } return dp[n]; } };
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