leetcode 279 solution

 279. Perfect Squares

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

solution:

class Solution {

public:

    int numSquares(int n) {

        //vector for updating the dp array/values

        vector<int> dp(n+1,INT_MAX);

        //base case

        dp[0]=0;

        int count = 1;

        while(count*count <= n) {

        int sq = count*count;

        for(int i = sq; i < n+1; i++) {

            dp[i] = min(dp[i-sq] + 1,dp[i]);

        }

        count++;

    }

    return dp[n];

    }

};