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Update topN functions to return their top ranges

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Infiltrator 2015-12-08 18:58:18 +11:00 • committed by Tim Sviridov
parent 8da9dbc2ae
commit 865afe1b39
1 changed files with 19 additions and 3 deletions
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22
std/algorithm/sorting.d
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@ -2152,7 +2152,7 @@ BUGS:
Stable topN has not been implemented yet.
*/
void topN(alias less = "a < b",
auto topN(alias less = "a < b",
SwapStrategy ss = SwapStrategy.unstable,
Range)(Range r, size_t nth)
if (isRandomAccessRange!(Range) && hasLength!Range)
@ -2162,6 +2162,7 @@ void topN(alias less = "a < b",
static assert(ss == SwapStrategy.unstable,
"Stable topN not yet implemented");
auto ret = r[0 .. nth];
while (r.length > nth)
{
auto pivot = uniform(0, r.length);
@ -2173,7 +2174,7 @@ void topN(alias less = "a < b",
pivot = r.length - right.length;
if (pivot == nth)
{
return;
return ret;
}
if (pivot < nth)
{
@ -2187,6 +2188,7 @@ void topN(alias less = "a < b",
r = r[0 .. pivot];
}
}
return ret;
}
///
@ -2196,6 +2198,12 @@ void topN(alias less = "a < b",
auto n = 4;
topN!"a < b"(v, n);
assert(v[n] == 9);
// bug 12987
int[] a = [ 25, 7, 9, 2, 0, 5, 21 ];
auto t = topN(a, n);
sort(t);
assert(t == [0, 2, 5, 7]);
}
@safe unittest
@ -2283,7 +2291,7 @@ Params:
r1 = The first range.
r2 = The second range.
*/
void topN(alias less = "a < b",
auto topN(alias less = "a < b",
SwapStrategy ss = SwapStrategy.unstable,
Range1, Range2)(Range1 r1, Range2 r2)
if (isRandomAccessRange!(Range1) && hasLength!Range1 &&
@ -2298,6 +2306,7 @@ void topN(alias less = "a < b",
{
heap.conditionalInsert(r2.front);
}
return r1;
}
///
@ -2308,6 +2317,13 @@ unittest
topN(a, b);
sort(a);
assert(a == [0, 1, 2, 2, 3]);
// bug 12987
int[] c = [ 5, 7, 2, 6, 7 ];
int[] d = [ 2, 1, 5, 6, 7, 3, 0 ];
auto t = topN(c, d);
sort(t);
assert(t == [ 0, 1, 2, 2, 3 ]);
}
/**