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| class Solution {
public int numberOfArithmeticSlices(int[] nums) {
int ans = 0, n = nums.length;
Map<Long, Integer>[] f = new Map[n];
for (int i = 0; i < n; ++i) {
f[i] = new HashMap<>();
}
for (int i = 0; i < n; ++i) {
for (int j = 0; j < i; ++j) {
long d = (long) nums[i] - nums[j];
int cnt = f[j].getOrDefault(d, 0);
ans += cnt;
f[i].put(d, f[i].getOrDefault(d, 0) + cnt + 1);
}
}
return ans;
}
}
|
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