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@@ -0,0 +1,17 @@
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+func fourSumCount(A []int, B []int, C []int, D []int) (cnt int) {
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+ n := len(A)
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+ m := make(map[int]int)
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+ for i := 0; i < n; i++ {
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+ for j := 0; j < n; j++ {
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+ m[C[i]+D[j]]++
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+ }
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+ }
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+ for i := 0; i < n; i++ {
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+ for j := 0; j < n; j++ {
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+ if val, ok := m[-A[i]-B[j]]; ok {
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+ cnt += val
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+ }
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+ }
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+ }
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+ return
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+}
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