leetcode@ [279]Perfect Squares

https://leetcode.com/problems/perfect-squares/

Given a positive integer n, find the least number of perfect square numbers (for example,

1, 4, 9, 16, ...

) which sum to n.

For example, given n =

12

, return

3

because

12 = 4 + 4 + 4

; given n =

13

, return

2

because

13 = 4 + 9

.

class Solution {
public:
int getMaximumSquare(int n){
int ret = (int)sqrt(n);
return ret;
}
int dfs(int load, vector<int> &dp){
if(dp[load]) return dp[load];
if(load == 0){
return 0;
}

int next = getMaximumSquare(load);
int Min = numeric_limits<int>::max();
for(int v=next;v>=1;v--){
if(load-v*v >= 0){
Min = min(Min, dfs(load-v*v, dp));
}
}
dp[load] = Min + 1;
return dp[load];
}
int numSquares(int n) {
vector<int> dp(n+1);
for(int i=0;i<dp.size();++i) dp[i] = 0;

dp
= dfs(n, dp);
return dp
;
}
};