473. Matchsticks to Square
Posted
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了473. Matchsticks to Square相关的知识,希望对你有一定的参考价值。
Remember the story of Little Match Girl? By now, you know exactly what matchsticks the little match girl has, please find out a way you can make one square by using up all those matchsticks. You should not break any stick, but you can link them up, and each matchstick must be used exactly one time.
Your input will be several matchsticks the girl has, represented with their stick length. Your output will either be true or false, to represent whether you could make one square using all the matchsticks the little match girl has.
Example 1:
Input: [1,1,2,2,2] Output: true Explanation: You can form a square with length 2, one side of the square came two sticks with length 1.
Example 2:
Input: [3,3,3,3,4] Output: false Explanation: You cannot find a way to form a square with all the matchsticks.
Note:
- The length sum of the given matchsticks is in the range of
0
to10^9
. - The length of the given matchstick array will not exceed
15
.
Subscribe to see which companies asked this question.
递归,dfs
public class Solution {
public boolean makesquare(int[] nums) {
int sum = 0, l = 0;
if (nums.length == 0) {
return false;
}
for (int i = 0; i < nums.length; i++) {
sum += nums[i];
}
if (sum % 4 != 0) {
return false;
}
Arrays.sort(nums);
l = sum / 4;
return helper(0, 0, 0, 0, nums, nums.length - 1, l);
}
public boolean helper(int l1, int l2, int l3, int l4, int[] nums, int end, int l) {
boolean f1 = false, f2 = false, f3 = false, f4 = false;
if (end < 0) {
if (l1 == l && l2 == l && l3 == l && l4 == l) {
return true;
} else {
return false;
}
}
int tmp = nums[end];
if (l1 + tmp <= l) {
f1 = helper(l1 + tmp, l2, l3, l4, nums, end - 1, l);
}
if (f1) {
return f1;
}
if (l2 + tmp <= l) {
f2 = helper(l1, l2 + tmp, l3, l4, nums, end - 1, l);
}
if (f2) {
return f2;
}
if (l3 + tmp <= l) {
f3 = helper(l1, l2, l3 + tmp, l4, nums, end - 1, l);
}
if (f3) {
return f3;
}
if (l4 + tmp <= l) {
f4 = helper(l1, l2, l3, l4 + tmp, nums, end - 1, l);
}
return f4;
}
}
以上是关于473. Matchsticks to Square的主要内容,如果未能解决你的问题,请参考以下文章
LeetCode 473 - Matchsticks to Square - Medium (Python)
[LeetCode] Matchsticks to Square 火柴棍组成正方形
Matchsticks to Square && Grammar: reverse an primative array
Leetcode: Matchsticks to Square && Grammar: reverse an primative array