add

Author: Hawstein

19.10.cpp

@@ -0,0 +1,15 @@
+#include <iostream>
+using namespace std;
+
+int Rand5(){
+    int x = ~(1<<31); // max int
+    while(x > 5)
+        x = Rand7();
+    return x;
+}
+
+
+
+int main(){
+    return 0;
+}

19.11

@@ -0,0 +1,30 @@
+#include <iostream>
+#include <algorithm>
+using namespace std;
+
+void PrintPairSum(int a[], int n, int sum){
+    if(a==NULL || n<2) return;
+    
+    sort(a, a+n);
+    int low = 0, high = n-1;
+    while(low < high){
+        if(a[low]+a[high] > sum)
+            --high;
+        else if(a[low]+a[high] < sum)
+            ++low;
+        else{
+            cout<<a[low]<<" "<<a[high]<<endl;
+            ++low; --high;
+        }
+            
+    }
+}
+
+int main(){
+    int n = 6, sum = 6;
+    int a[] = {
+        1, 2, 3, 4, 5, 6
+    };
+    PrintPairSum(a, n, sum);
+    return 0;
+}

19.11.cpp

@@ -0,0 +1,78 @@
+#include <iostream>
+using namespace std;
+
+enum Check{
+    ROW, COLUMN, DIAGONAL, REDIAGONAL
+};
+
+int CheckRowColumn(int board[], int n, Check check){
+    int type = 0;
+    for(int i=0; i<n; ++i){
+        bool found = true;
+        for(int j=0; j<n; ++j){
+            int k = 0;
+            if(check == ROW)
+                k = i * n + j;
+            else
+                k = i + j * n;
+            if(j == 0){
+                type = board[k];
+            }
+            else if(board[k] != type){
+                found = false;
+                break; // 有一个不满足，检查下一行
+            }
+        }
+        if(found) return type;
+    }
+    return 0;
+}
+int CheckDiagonal(int board[], int n, Check check){
+    int type = 0;
+    bool found = true;
+    // 主对角
+    for(int i=0; i<n; ++i){
+        int k = 0;
+        if(check == DIAGONAL)
+            k = i + i * n;
+        else
+            k = i + (n-1-i) * n;
+        if(i == 0){
+            type = board[k];
+        }
+        else if(board[k] != type){
+            found = false;
+            break;
+        }
+    }
+    if(found) return type;
+
+    return 0;
+}
+int HasWon(int board[], int n){
+    int type = 0;
+    type = CheckRowColumn(board, n, ROW);
+    if(type != 0) return type;
+    type = CheckRowColumn(board, n, COLUMN);
+    if(type != 0) return type;
+    type = CheckDiagonal(board, n, DIAGONAL);
+    if(type != 0) return type;
+    type = CheckDiagonal(board, n, REDIAGONAL);
+    if(type != 0) return type;
+
+    return 0;
+}
+int main(){
+    int n = 3; // 3*3
+    int board[] = {
+        2, 2, 1,
+        2, 1, 1,
+        1, 2, 0,
+    };
+    int type = HasWon(board, n);
+    if(type != 0)
+        cout<<type<<" won!"<<endl;
+    else
+        cout<<"nobody won!"<<endl;
+    return 0;
+}

19.2

@@ -0,0 +1,25 @@
+#include <iostream>
+using namespace std;
+
+int NumZeros(int n){
+    if(n < 0) return -1;
+    int num = 0;
+    while((n /= 5) > 0){
+        num += n;
+    }
+    return num;
+}
+int NumZeros1(int n){
+    if(n < 0) return -1;
+    int num = 0;
+    for(int i = 5; n/i > 0; i *= 5)
+        num += n/i;
+    return num;
+}
+int main(){
+    for(int i=1; i<100; ++i){
+        if(NumZeros(i) == NumZeros1(i))
+            cout<<i<<endl;
+    }
+    return 0;
+}

19.2.cpp

@@ -0,0 +1,22 @@
+#include <iostream>
+using namespace std;
+
+int Max1(int a, int b){
+    int c[2] = {
+        a, b
+    };
+    int z = a - b;
+    z = (z>>31) & 1;
+    return c[z];
+}
+int Max2(int a, int b){
+    int z = a - b;
+    int k = (z>>31) & 1;
+    return a - k * z;
+}
+int main(){
+    int a = 5, b = 10;
+    cout<<Max1(a, b)<<endl;
+    cout<<Max2(a, b)<<endl;
+    return 0;
+}

19.3

@@ -0,0 +1,60 @@
+#include <iostream>
+#include <cstring>
+using namespace std;
+
+struct Result{
+    int hits;
+    int pseudo_hits;
+};
+
+Result Estimate(const char* solution, const char* guess){
+    Result res;
+    res.hits = 0;
+    res.pseudo_hits = 0;
+    int solution_mask = 0;
+    for(int i=0; i<4; ++i){
+        solution_mask |= 1 << (solution[i] - 'A');
+    }
+    for(int i=0; i<4; ++i){
+        if(guess[i] == solution[i])
+            ++res.hits;
+        else if(solution_mask & ( 1<<(guess[i] - 'A')))
+            ++res.pseudo_hits;
+    }
+    return res;
+}
+
+int Min(int a, int b){
+    return a < b ? a : b;
+}
+Result Estimate1(const char* solution, const char* guess){
+    Result res;
+    res.hits = 0;
+    res.pseudo_hits = 0;
+    int num = 26 + 5;
+    int guess_count[num], solution_count[num];
+    memset(guess_count, 0, sizeof(guess_count));
+    memset(solution_count, 0, sizeof(solution_count));
+    for(int i=0; i<4; ++i){
+        if(guess[i] == solution[i])
+            ++res.hits;
+        ++guess_count[(int)(guess[i]-'A')];
+        ++solution_count[(int)(solution[i]-'A')];
+    }
+    char color[] = "RGBY";
+    for(int i=0; i<4; ++i){
+        int idx = (int)(color[i] - 'A');
+        res.pseudo_hits += Min(guess_count[idx], solution_count[idx]);
+    }
+    res.pseudo_hits -= res.hits;
+    return res;
+}
+int main(){
+    char solution[] = "RYGB";
+    char guess[] = "YRRR";
+    Result res = Estimate(solution, guess);
+    cout<<res.hits<<" "<<res.pseudo_hits<<endl;
+    Result res1 = Estimate1(solution, guess);
+    cout<<res1.hits<<" "<<res1.pseudo_hits<<endl;
+    return 0;
+}

19.3.cpp

@@ -0,0 +1,37 @@
+#include <iostream>
+using namespace std;
+
+bool g_Invalid = false;
+
+int GetMaxSum(int a[], int n){
+    if(a==NULL || n<=0){
+        g_Invalid = true;
+        return 0;
+    }
+    g_Invalid = false;
+    
+    int max_sum = 1<<31; // Min Int
+    int cur_sum = 0;
+    for(int i=0; i<n; ++i){
+        if(cur_sum <= 0)
+            cur_sum = a[i];
+        else
+            cur_sum += a[i];
+
+        if(cur_sum > max_sum)
+            max_sum = cur_sum;
+    }
+
+    return max_sum;
+}
+int main(){
+    int a[] = {
+        -2, -8, 3, -2, 4, -10
+    };
+    int max_sum = GetMaxSum(a, 6);
+    if(g_Invalid)
+        cout<<"Invalid Input!"<<endl;
+    else
+        cout<<max_sum<<endl;
+    return 0;
+}

19.4

@@ -0,0 +1,29 @@
+#include <iostream>
+using namespace std;
+
+int Add1(int a, int b){
+    char *c = (char*)a;
+    return (int)&c[b]; // c+sizeof(char)*b=a + b
+}
+int Add2(int a, int b){
+    if(b == 0) return a;
+    int sum = a ^ b; // 各位相加，不计进位
+    int carry = (a & b) << 1; // 记下进位
+    return Add2(sum, carry); // 求sum和carry的和
+}
+int Add3(int a, int b){
+    while(b != 0){
+        int sum = a ^ b;
+        int carry = (a & b) << 1;
+        a = sum;
+        b = carry;
+    }
+    return a;
+}
+int main(){
+    int a = 1123927350, b = -134310;
+    cout<<Add1(a, b)<<endl;
+    cout<<Add2(a, b)<<endl;
+    cout<<Add3(a, b)<<endl;
+    return 0;
+}

19.4.cpp

@@ -0,0 +1,26 @@
+#include <iostream>
+#include <cstdlib>
+using namespace std;
+
+void Swap(int &a, int &b){// 有可能swap同一变量，不能用异或版本
+    int t = a;
+    a = b;
+    b = t;
+}
+void RandomShuffle(int a[], int n){
+    for(int i=0; i<n; ++i){
+        int j = rand() % (n-i) + i;// 产生i到n-1间的随机数
+        Swap(a[i], a[j]);
+    }
+}
+int main(){
+    srand((unsigned)time(0));
+    int n = 9;
+    int a[] = {
+        1, 2, 3, 4, 5, 6, 7, 8, 9
+    };
+    RandomShuffle(a, n);
+    for(int i=0; i<n; ++i)
+        cout<<a[i]<<endl;
+    return 0;
+}

19.5

@@ -0,0 +1,26 @@
+#include <iostream>
+#include <cstdlib>
+using namespace std;
+
+void Swap(int &a, int &b){// 有可能swap同一变量，不能用异或版本
+    int t = a;
+    a = b;
+    b = t;
+}
+void PickMRandomly(int a[], int n, int m){
+    for(int i=0; i<m; ++i){
+        int j = rand() % (n-i) + i;// 产生i到n-1间的随机数
+        Swap(a[i], a[j]);
+    }
+}
+int main(){
+    srand((unsigned)time(0));
+    int n = 9, m = 5;
+    int a[] = {
+        1, 2, 3, 4, 5, 6, 7, 8, 9
+    };
+    PickMRandomly(a, n, m);
+    for(int i=0; i<m; ++i)
+        cout<<a[i]<<endl;
+    return 0;
+}

19.5.cpp

@@ -0,0 +1,36 @@
+#include <iostream>
+using namespace std;
+
+int Count2s(int n){
+    int count = 0;
+    int factor = 1;
+    int low = 0, cur = 0, high = 0;
+
+    while(n/factor != 0){
+        low = n - (n/factor) * factor;
+        cur = (n/factor) % 10;
+        high = n / (factor*10);
+
+        switch(cur){
+        case 0:
+        case 1:
+            count += high * factor;
+            break;
+        case 2:
+            count += high * factor + low + 1;
+            break;
+        default:
+            count += (high + 1) * factor;
+            break;
+        }
+
+        factor *= 10;
+    }
+
+    return count;
+}
+int main(){
+    for(int i=1; i<1000; ++i)
+        cout<<i<<" "<<Count2s(i)<<endl;
+    return 0;
+}