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Perfect Squares

Tags : dynamic-programming, leetcode, cpp, medium

Problem Statement - link #

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.

Examples #

Example 1:

Input: n = 12
Output: 3
Explanation: 12 = 4 + 4 + 4.

Example 2:

Input: n = 13
Output: 2
Explanation: 13 = 4 + 9.

Constraints #

Solutions #


class Solution {
public:
    int numSquares(int n) {
        vector<int> dp(n+1,n+1);
        dp[0] = 0;
        int i=1;
        while(i*i<=n){
            for(int j=i*i; j<dp.size(); j++){
                dp[j] = min(dp[j-i*i]+1,dp[j]);
            }
            i++;
        }
        return dp[n];
    }
};