计数排序

\[ \begin{array}{ll} 1 & \textbf{Input. } \text{An array } A \text{ consisting of }n\text{ positive integers no greater than } w. \\ 2 & \textbf{Output. } \text{Array }A\text{ after sorting in nondecreasing order stably.} \\ 3 & \textbf{Method. } \\ 4 & \textbf{for }i\gets0\textbf{ to }w\\ 5 & \qquad cnt[i]\gets0\\ 6 & \textbf{for }i\gets1\textbf{ to }n\\ 7 & \qquad cnt[A[i]]\gets cnt[A[i]]+1\\ 8 & \textbf{for }i\gets1\textbf{ to }w\\ 9 & \qquad cnt[i]\gets cnt[i]+cnt[i-1]\\ 10 & \textbf{for }i\gets n\textbf{ downto }1\\ 11 & \qquad B[cnt[A[i]]]\gets A[i]\\ 12 & \qquad cnt[A[i]]\gets cnt[A[i]]-1\\ 13 & \textbf{return } B \end{array} \]

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const int N = 100010;
const int W = 100010;

int n, w, a[N], cnt[W], b[N];

void counting_sort() {
    memset(cnt, 0, sizeof(cnt));
    for (int i = 1; i <= n; ++i) ++cnt[a[i]];
    for (int i = 1; i <= w; ++i) cnt[i] += cnt[i - 1];
    for (int i = n; i >= 1; --i) b[cnt[a[i]]--] = a[i];
}

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N = W = 100010
n = w = 0
a = b = [0] * N
cnt = [0] * W

def counting_sort():
    for i in range(1, n + 1):
        cnt[a[i]] += 1
    for i in range(1, w + 1):
        cnt[i] += cnt[i - 1]
    for i in range(n, 0, -1):
        b[cnt[a[i]] - 1] = a[i]
        cnt[a[i]] -= 1