[Leetcode刷题]Perfect Squares
2016-06-25 08:42
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Given a positive integer n, find the least number of perfect square numbers (for example,
For example, given n =
Thoughts
dp[x + y^2] = min( dp[x] + 1 , dp[x + y^2])
Solutions
<span style="font-size:14px;">public class Solution {
public int numSquares(int n) {
int[] dp = new int[n+1];
Arrays.fill(dp, Integer.MAX_VALUE);
for(int i = 1; i*i <= n; i++){
dp[i*i] = 1;
}
for(int x = 1; x <= n; x++){
for(int y = 1; x + y *y <= n; y++){
dp[x + y * y] = Math.min(dp[x + y * y], dp[x] + 1);
}
}
return dp
;
}
}</span>
1, 4, 9, 16, ...) which sum to n.
For example, given n =
12, return
3because
12 = 4 + 4 + 4; given n =
13, return
2because
13 = 4 + 9.
Thoughts
dp[x + y^2] = min( dp[x] + 1 , dp[x + y^2])
Solutions
<span style="font-size:14px;">public class Solution {
public int numSquares(int n) {
int[] dp = new int[n+1];
Arrays.fill(dp, Integer.MAX_VALUE);
for(int i = 1; i*i <= n; i++){
dp[i*i] = 1;
}
for(int x = 1; x <= n; x++){
for(int y = 1; x + y *y <= n; y++){
dp[x + y * y] = Math.min(dp[x + y * y], dp[x] + 1);
}
}
return dp
;
}
}</span>
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