DP
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13class Solution {
public int numSquares(int n) {
int[] dp = new int[n+1];
Arrays.fill(dp, Integer.MAX_VALUE);
dp[0] = 0;
for(int i = 1; i <= n; i++){
for(int j = 1; j * j <= i; j++){
dp[i] = Math.min(dp[i], dp[i - j*j] + 1);
}
}
return dp[n];
}
}