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@@ -0,0 +1,31 @@
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+func makesquare(nums []int) bool {
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+ n := len(nums)
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+ if n < 4 {
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+ return false
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+ }
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+ sum := 0
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+ for _, i := range nums {
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+ sum += i
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+ }
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+ if sum%4 != 0 {
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+ return false
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+ }
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+ sort.Sort(sort.Reverse(sort.IntSlice(nums))) // It's super effective!
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+ return dfs(nums, make([]int, 4), n, 0, sum/4)
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+}
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+
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+func dfs(nums []int, sums []int, n int, idx int, target int) bool {
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+ if idx == n {
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+ return sums[0] == target && sums[1] == target && sums[2] == target
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+ }
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+ for i := 0; i < 4; i++ {
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+ if sums[i]+nums[idx] <= target {
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+ sums[i] += nums[idx]
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+ if dfs(nums, sums, n, idx+1, target) {
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+ return true
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+ }
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+ sums[i] -= nums[idx]
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+ }
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+ }
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+ return false
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+}
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