Given an integer n, return the least number of perfect square numbers that sum to n.
A perfect square is an integer that is the square of an integer; in other words, it is the product of some integer with itself. For example, 1, 4, 9, and 16 are perfect squares while 3 and 11 are not.
Example 1:
Input: n = 12 Output: 3 Explanation: 12 = 4 + 4 + 4.
Example 2:
Input: n = 13 Output: 2 Explanation: 13 = 4 + 9.
Constraints:
1 <= n <= 104
Code
Time Complexity: , Space Complexity:
class Solution {
public:
int numSquares(int n) {
vector<int> DP(n+1, 1e9);
DP[0] = 0;
for(int i = 1; i <= n; i++) {
for(int j = 1; pow(j, 2) <= i; j++) {
DP[i] = min(DP[i], 1 + DP[i - pow(j, 2)]);
}
}
return DP[n];
}
};