second

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "files.associations": {
+        "iostream": "cpp"
+    }
+}

README.md

@@ -1,2 +1,59 @@
 # CSP
 
+## 高精度
+1. python打表
+2. 高精加和高精乘
+
+## 筛法
+1. 打表
+2. 素数筛
+   1. 埃氏筛
+```c++
+bool book[100000001];
+int prim[2000];
+int prn = 0;
+// 用埃氏筛法生成质数表
+void prime(int b)
+{
+    //初始化，默认全部都是质数
+    memset(book, true, sizeof(book));
+    book[1] = false; //1不是质数
+    int n = sqrt(b); //大于n的合数都被筛了，但是prim里面的素数会变少，看情况用
+    for (int i = 2; i <= n; i++)
+    {
+        if (book[i])
+        {
+            prim[prn++] = i;
+            //质数的倍数绝对不是质数，把所有质数的倍数全部设为false
+            for (int j = i; j <= b ; j+=i)
+                book[j] = false; // i*j<=b
+        }
+    }
+}
+```
+   2. 线性筛
+```c++
+bool book[100000001];
+int prim[2000];
+int prn = 0;
+// 用埃氏筛法生成质数表
+void prime(int b)
+{
+    //初始化，默认全部都是质数
+    memset(book, true, sizeof(book));
+    book[1] = false; //1不是质数
+    for (int i = 2; i <= n; i++)
+    {
+        if (book[i])
+        {
+            prim[prn++] = i;
+        }
+        for (int j = 0; j < prn && i * prim[j] < N; j++)
+        {
+            book[i * prim[j]] = false; // i*j<=b
+            if (i % prim[j] == 0)
+                break;
+        }
+    }
+}
+```

前缀和/CSP_202104-2.cpp

@@ -0,0 +1,64 @@
+#include <iostream>
+#include <math.h>
+#include <cstring>
+using namespace std;
+int x[601][601];
+int F[601][601];
+int line[601] = {0};
+/*
+一维index表示行数，二维index表示列数
+
+
+*/
+int main()
+{
+    int n, L, r, t;
+    cin >> n >> L >> r >> t;
+    for (int i = 0; i <= n; i++)
+    {
+        memset(line, 0, sizeof(line));
+        for (int j = 0; j <= n; j++)
+        {
+            if (i == 0 || j == 0)
+                F[i][j] = 0;
+            else
+            {
+                cin >> x[i][j];
+                line[j] = line[j - 1] + x[i][j];
+                F[i][j] = line[j] + F[i - 1][j];
+            }
+        }
+    }
+    // for (int i = 0; i <= n; i++)
+    // {
+    //     for (int j = 0; j <= n; j++)
+    //     {
+    //         cout << F[i][j] << " ";
+    //     }
+    //     cout << endl;
+    // }
+    int count = 0;
+    for (int i = 1; i <= n; i++)
+    {
+        for (int j = 1; j <= n; j++)
+        {
+            int i_up = (i - r - 1 > 0) ? i - r - 1 : 0;
+            int i_down = (i + r <= n) ? i + r : n;
+            int j_left = (j - r - 1 > 0) ? j - r - 1 : 0;
+            int j_right = (j + r <= n) ? j + r : n;
+            double average = (F[i_down][j_right] + F[i_up][j_left] - F[i_down][j_left] - F[i_up][j_right]);
+            // cout << average << " ";
+            // cout << (i_down - i_up) * (j_right - j_left) << " ";
+            // if ((i_down - i_up) * (j_right - j_left) == 24)
+            // {
+            //     cout << i << " " << j << " " << r << endl;
+            // }
+            average = average / (i_down - i_up) / (j_right - j_left);
+            if (average <= t)
+                count++;
+        }
+        // cout << endl;
+    }
+    cout << count;
+    return 0;
+}

筛法/1.md

@@ -0,0 +1,2 @@
+# luogu_P1217
+![](2021-09-23-15-35-38.png)

筛法/luogu_P1217_biao.cpp

@@ -0,0 +1,98 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int Prime(int x)
+{
+    if (x == 1 || x == 0)
+        return 0;
+    if (x == 2 || x == 3)
+        return 1;
+    if (x % 2 == 0 || x % 3 == 0)
+        return 0;
+    for (int i = 2; i <= x / 2; i++)
+    {
+        if (x % i == 0)
+            return 0;
+    }
+    return 1;
+}
+int main()
+{
+    freopen("D:/我的/大学/计算机类/1算法学习/CSP/筛法/P1217.txt", "w", stdout);
+    int d1, d2, d3, d4, d5, palindrome;
+    int k;
+    int a, b;
+    a = 5;
+    b = 100000000;
+    cout << "{";
+    //1
+    for (d1 = 1; d1 <= 9; d1 += 2)
+    {
+        palindrome = d1;
+        if (a > palindrome * 10)
+            break;
+        if (a <= palindrome && palindrome <= b && Prime(palindrome) == 1)
+            cout << palindrome << ",";
+        if (palindrome > b)
+            return 0;
+    }
+    //2
+    if (a <= 11 && 11 <= b)
+        cout << 11 << ",";
+    //3
+    for (d1 = 1; d1 <= 9; d1 += 2)
+        for (d2 = 0; d2 <= 9; d2++)
+        {
+            palindrome = 100 * d1 + 10 * d2 + d1;
+            if (a > palindrome * 10)
+                break;
+            if (a <= palindrome && palindrome <= b && Prime(palindrome) == 1)
+                cout << palindrome << ",";
+            if (palindrome > b)
+                return 0;
+        }
+    //5
+    for (d1 = 1; d1 <= 9; d1 += 2)
+        for (d2 = 0; d2 <= 9; d2++)
+            for (d3 = 0; d3 <= 9; d3++)
+            {
+                palindrome = 10000 * d1 + 1000 * d2 + 100 * d3 + 10 * d2 + d1;
+                if (a > palindrome * 10)
+                    break;
+                if (a <= palindrome && palindrome <= b && Prime(palindrome) == 1)
+                    cout << palindrome << ",";
+                if (palindrome > b)
+                    return 0;
+            }
+    //7
+    for (d1 = 1; d1 <= 9; d1 += 2)
+        for (d2 = 0; d2 <= 9; d2++)
+            for (d3 = 0; d3 <= 9; d3++)
+                for (d4 = 0; d4 <= 9; d4++)
+                {
+                    palindrome = 1000000 * d1 + 100000 * d2 + 10000 * d3 + 1000 * d4 + 100 * d3 + 10 * d2 + d1;
+                    if (a > palindrome * 10)
+                        break;
+                    if (a <= palindrome && palindrome <= b && Prime(palindrome) == 1)
+                        cout << palindrome << ",";
+                    if (palindrome > b)
+                        return 0;
+                }
+    //9
+    for (d1 = 1; d1 <= 9; d1 += 2)
+        for (d2 = 0; d2 <= 9; d2++)
+            for (d3 = 0; d3 <= 9; d3++)
+                for (d4 = 0; d4 <= 9; d4++)
+                    for (d5 = 0; d5 <= 9; d5++)
+                    {
+                        palindrome = 100000000 * d1 + 10000000 * d2 + 1000000 * d3 + 100000 * d4 + 10000 * d5 + 1000 * d4 + 100 * d3 + 10 * d2 + d1;
+                        if (a > palindrome * 10)
+                            break;
+                        if (a <= palindrome && palindrome <= b && Prime(palindrome) == 1)
+                            cout << palindrome << ",";
+                        if (palindrome > b)
+                            return 0;
+                    }
+    cout << "}";
+    return 0;
+}

高精度/luogu_P1009.cpp

@@ -0,0 +1,53 @@
+#include <bits/stdc++.h>
+using namespace std;
+void pplus(int *a, int *c)
+{
+    int jw = 0;
+    for (int i = 1; i <= 1000; i++)
+    {
+        c[i] += a[i] + jw;
+        jw = c[i] / 10;
+        c[i] %= 10;
+    }
+}
+void pmultiply(int *a, int c)
+{
+    int jw = 0;
+    for (int i = 0; i < 1000; i++)
+    {
+        a[i] = a[i] * c + jw;
+        jw = a[i] / 10;
+        a[i] %= 10;
+    }
+}
+//用高精度计算出 S = 1! + 2! + 3! + \cdots + n!S=1!+2!+3!+⋯+n!（n \le 50n≤50）
+int main()
+{
+    // python 打表
+    // string a[51] = {"0", "1", "3", "9", "33", "153", "873", "5913", "46233", "409113", "4037913", "43954713", "522956313", "6749977113", "93928268313", "1401602636313", "22324392524313", "378011820620313", "6780385526348313", "128425485935180313", "2561327494111820313", "53652269665821260313", "1177652997443428940313", "27029669736328405580313", "647478071469567844940313", "16158688114800553828940313", "419450149241406189412940313", "11308319599659758350180940313", "316196664211373618851684940313", "9157958657951075573395300940313", "274410818470142134209703780940313", "8497249472648064951935266660940313", "271628086406341595119153278820940313", "8954945705218228090637347680100940313", "304187744744822368938255957323620940313", "10637335711130967298604907294846820940313", "382630662501032184766604355445682020940313", "14146383753727377231082583937026584420940313", "537169001220328488991089808037100875620940313", "20935051082417771847631371547939998232420940313", "836850334330315506193242641144055892504420940313", "34289376947494122614363304694584807557656420940313", "1439295494700374021157505910939096377494040420940313", "61854558558074209658512637979453093884758552420940313", "2720126133346522977702138448994068984204397080420940313", "122342346998826717539665299944651784048588130840420940313", "5624964506810915667389970728744906677010239883800420940313", "264248206017979096310354325882356886646207872272920420940313", "12678163798554051767172643373255731925167694226950680420940313", "620960027832821612639424806694551108812720525606160920420940313", "31035053229546199656252032972759319953190362094566672920420940313"};
+    // int n;
+    // cin >> n;
+    // cout << a[n];
+
+    // 高精度模板
+    int n;
+    cin >> n;
+    int sum[51][1000];
+    memset(sum, 0, sizeof(int) * 1000);
+    sum[0][0] = 1;
+    for (int i = 1; i < n + 1; i++)
+    {
+        pmultiply(sum[i], i);
+    }
+    for (int i = 2; i < n + 1; i++)
+    {
+        pplus(sum[i - 1], sum[i]);
+    }
+    for (int i = 999; i >= 0; i--)
+    {
+        while (sum[n][i] == 0)
+            i--;
+        cout << sum[n][i];
+    }
+    return 0;
+}

高精度/luogu_P1009.py

@@ -0,0 +1,13 @@
+f=open('高精度\point.txt','w')
+sum=1
+i=2
+last=1
+n=50
+while i<=n:
+    last*=i
+    sum+=last
+    i+=1
+    f.write('"')
+    f.write(str(sum))
+    f.write('",')
+f.close()

高精度/point.txt

@@ -0,0 +1 @@
+"3","9","33","153","873","5913","46233","409113","4037913","43954713","522956313","6749977113","93928268313","1401602636313","22324392524313","378011820620313","6780385526348313","128425485935180313","2561327494111820313","53652269665821260313","1177652997443428940313","27029669736328405580313","647478071469567844940313","16158688114800553828940313","419450149241406189412940313","11308319599659758350180940313","316196664211373618851684940313","9157958657951075573395300940313","274410818470142134209703780940313","8497249472648064951935266660940313","271628086406341595119153278820940313","8954945705218228090637347680100940313","304187744744822368938255957323620940313","10637335711130967298604907294846820940313","382630662501032184766604355445682020940313","14146383753727377231082583937026584420940313","537169001220328488991089808037100875620940313","20935051082417771847631371547939998232420940313","836850334330315506193242641144055892504420940313","34289376947494122614363304694584807557656420940313","1439295494700374021157505910939096377494040420940313","61854558558074209658512637979453093884758552420940313","2720126133346522977702138448994068984204397080420940313","122342346998826717539665299944651784048588130840420940313","5624964506810915667389970728744906677010239883800420940313","264248206017979096310354325882356886646207872272920420940313","12678163798554051767172643373255731925167694226950680420940313","620960027832821612639424806694551108812720525606160920420940313","31035053229546199656252032972759319953190362094566672920420940313",