{"id":376,"date":"2026-03-24T19:51:31","date_gmt":"2026-03-24T11:51:31","guid":{"rendered":"https:\/\/jiangqvweihuan.cn\/?p=376"},"modified":"2026-03-30T18:37:37","modified_gmt":"2026-03-30T10:37:37","slug":"%e9%80%86%e5%ba%8f%e5%af%b9","status":"publish","type":"post","link":"https:\/\/jiangqvweihuan.cn\/index.php\/2026\/03\/24\/%e9%80%86%e5%ba%8f%e5%af%b9\/","title":{"rendered":"\u7b97\u6cd5\u5fc3\u4f20\u00b7\u9006\u5e8f\u5bf9"},"content":{"rendered":"\n

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\"\"<\/div><\/figure>\n\n\n\n

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#include <bits\/stdc++.h>\nusing namespace std;\n\nconst int N = 500005;\nint a[N];\nint h[N];\nlong long ans = 0;\n\n\/\/\u6a21\u62df\u5408\u5e76\nvoid merge(int l, int r, int mid)\n{\n    int pos = l;\n    int i = l;\n    int j = mid + 1;\n    while (i <= mid && j <= r)\n    {\n        if (a[i] > a[j])\n        {\n            h[pos++] = a[j++];\n            \/\/ \u5f53\u51fa\u73b0\u53f3\u5e8f\u5217\u7684\u6570\u6bd4\u5de6\u5e8f\u5217\u7684\u8fd8\u5c0f\u65f6\uff0c\u4ee3\u8868\u7740\u8fd9\u65f6\u5019\u7684\u5de6\u5e8f\u5217\u6240\u6709\u6570\u90fd\u662f\u8fd9\u4e2a\u6570\u7684\u9006\u5e8f\u5bf9\n            ans += (mid - i + 1);\n        }\n        else\n        {\n            h[pos++] = a[i++];\n        }\n    }\n    while (i <= mid)\n        h[pos++] = a[i++];\n    while (j <= r)\n        h[pos++] = a[j++];\n    for (int k = l; k <= r; ++k)\n    {\n        a[k] = h[k];\n    }\n}\n\n\/\/\u6a21\u62df\u5206\u7ec4(\u9012\u5f52)\nvoid f(int l, int r)\n{\n    int mid = l + ((r - l) >> 1);\n    if (l == r)\n        return;\n    f(l, mid);\n    f(mid + 1, r);\n    merge(l, r, mid);\n}\n\nsigned main()\n{\n    int n;\n    cin >> n;\n    for (int i = 1; i <= n; ++i)\n    {\n        cin >> a[i];\n    }\n    f(1, n);\n    cout << ans;\n}<\/code><\/pre>\n\n\n\n
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#include <bits\/stdc++.h>\nusing namespace std;\n\nconst int N = 500005;\nint a[N], tmp[N];\nlong long ans = 0;\n\nvoid merge(int l, int mid, int r)\n{\n    int i = l, j = mid + 1, k = l;\n    while (i <= mid && j <= r)\n    {\n        if (a[i] > a[j])\n        {\n            tmp[k++] = a[j++];\n            ans += (mid - i + 1);\n        }\n        else\n        {\n            tmp[k++] = a[i++];\n        }\n    }\n    while (i <= mid)\n        tmp[k++] = a[i++];\n    while (j <= r)\n        tmp[k++] = a[j++];\n    for (int p = l; p <= r; ++p)\n        a[p] = tmp[p];\n}\n\nint main()\n{\n    int n;\n    cin >> n;\n    for (int i = 1; i <= n; ++i)\n        cin >> a[i];\n\n    \/\/ \u81ea\u5e95\u5411\u4e0a\u5f52\u5e76\n    \/\/ len <<= 1 \u7b49\u4ef7\u4e8elen *= 2\uff0c\u53ea\u4e0d\u8fc7\u524d\u8005\u662f\u4f4d\u8fd0\u7b97\u6548\u7387\u66f4\u9ad8\n    for (int len = 1; len < n; len <<= 1)\n    {\n        for (int l = 1; l + len <= n; l += (len << 1))\n        {\n            int mid = l + len - 1;\n            int r = min(l + (len << 1) - 1, n);\n            merge(l, mid, r);\n        }\n    }\n\n    cout << ans;\n    return 0;\n}<\/code><\/pre>\n\n\n\n
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\u4e8c\u3001\u7ecf\u5178\u4f8b\u9898<\/h2>\n\n\n\n
P1908 \u9006\u5e8f\u5bf9 – \u6d1b\u8c37<\/a><\/p>\n\n\n\n
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