Weekly LeetCode Algorithm Questions (19)
Subject: 279. 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.
solution analysis
This problem is basically the same as finding the number of paths to add to a specified number, but it is replaced by adding a square number each time.
C++ code
class Solution {
public:
int numSquares(int n) {
int * dp = new int[n + 1];
dp[0] = 0;
dp[1] = 1;
for (int i = 2; i <= n; i++) {
dp[i] = INT_MAX;
for (int j = 1; j * j <= i; j++) {
dp[i] = min(dp[i], dp[i - j * j] + 1);
}
}
return dp[n];
}
};