2021-10-14 Daily-Challenge

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In: DailyChallenge
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Today I have done leetcode's October LeetCoding Challenge with cpp.

October LeetCoding Challenge 14

Description

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

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
int answer[10001];
auto _ = [](){
  for(int i = 1; i < 10001; ++i) {
    answer[i] = INT_MAX;
    int bound = sqrt(i);
    for(int j = 1; j <= bound; ++j) {
      answer[i] = min(answer[i], answer[i - j * j] + 1);
    }
  }
  return 0;
}();
class Solution {
public:
  int numSquares(int n) {
    return answer[n];
  }
};

// Accepted
// 588/588 cases passed (2 ms)
// Your runtime beats 96.2 % of cpp submissions
// Your memory usage beats 82.23 % of cpp submissions (6.1 MB)
Algorithm