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krahets
2023-09-10 18:37:26 +08:00
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commit e48716c883
6 changed files with 192 additions and 19 deletions
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85
chapter_computational_complexity/iteration_and_recursion.md
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@ -158,7 +158,15 @@ status: new
=== "C"
```c title="iteration.c"
[class]{}-[func]{forLoop}
/* for 循环 */
int forLoop(int n) {
int res = 0;
// 循环求和 1, 2, ..., n-1, n
for (int i = 1; i <= n; ++i) {
res += i;
}
return res;
}
```
=== "Zig"
@ -344,7 +352,17 @@ status: new
=== "C"
```c title="iteration.c"
[class]{}-[func]{whileLoop}
/* while 循环 */
int whileLoop(int n) {
int res = 0;
int i = 1; // 初始化条件变量
// 循环求和 1, 2, ..., n-1, n
while (i <= n) {
res += i;
i++; // 更新条件变量
}
return res;
}
```
=== "Zig"
@ -539,7 +557,19 @@ status: new
=== "C"
```c title="iteration.c"
[class]{}-[func]{whileLoopII}
/* while 循环（两次更新） */
int whileLoopII(int n) {
int res = 0;
int i = 1; // 初始化条件变量
// 循环求和 1, 4, ...
while (i <= n) {
res += i;
// 更新条件变量
i++;
i *= 2;
}
return res;
}
```
=== "Zig"
@ -724,7 +754,23 @@ status: new
=== "C"
```c title="iteration.c"
[class]{}-[func]{nestedForLoop}
/* 双层 for 循环 */
char *nestedForLoop(int n) {
// n * n 为对应点数量，"(i, j), " 对应字符串长最大为 6+10*2，加上最后一个空字符 \0 的额外空间
int size = n * n * 26 + 1;
char *res = malloc(size * sizeof(char));
// 循环 i = 1, 2, ..., n-1, n
for (int i = 1; i <= n; ++i) {
// 循环 j = 1, 2, ..., n-1, n
for (int j = 1; j <= n; ++j) {
char tmp[26];
snprintf(tmp, sizeof(tmp), "(%d, %d), ", i, j);
strncat(res, tmp, size - strlen(res) - 1);
}
}
return res;
}
```
=== "Zig"
@ -910,7 +956,16 @@ status: new
=== "C"
```c title="recursion.c"
[class]{}-[func]{recur}
/* 递归 */
int recur(int n) {
// 终止条件
if (n == 1)
return 1;
// 递：递归调用
int res = recur(n - 1);
// 归：返回结果
return n + res;
}
```
=== "Zig"
@ -1091,7 +1146,14 @@ status: new
=== "C"
```c title="recursion.c"
[class]{}-[func]{tailRecur}
/* 尾递归 */
int tailRecur(int n, int res) {
// 终止条件
if (n == 0)
return res;
// 尾递归调用
return tailRecur(n - 1, res + n);
}
```
=== "Zig"
@ -1278,7 +1340,16 @@ status: new
=== "C"
```c title="recursion.c"
[class]{}-[func]{fib}
/* 斐波那契数列：递归 */
int fib(int n) {
// 终止条件 f(1) = 0, f(2) = 1
if (n == 1 || n == 2)
return n - 1;
// 递归调用 f(n) = f(n-1) + f(n-2)
int res = fib(n - 1) + fib(n - 2);
// 返回结果 f(n)
return res;
}
```
=== "Zig"

19
chapter_greedy/greedy_algorithm.md
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@ -264,7 +264,24 @@ status: new
=== "C"
```c title="coin_change_greedy.c"
[class]{}-[func]{coinChangeGreedy}
/* 零钱兑换：贪心 */
int coinChangeGreedy(int* coins, int size, int amt) {
// 假设 coins 列表有序
int i = size - 1;
int count = 0;
// 循环进行贪心选择，直到无剩余金额
while (amt > 0) {
// 找到小于且最接近剩余金额的硬币
while (i > 0 && coins[i] > amt) {
i--;
}
// 选择 coins[i]
amt -= coins[i];
count++;
}
// 若未找到可行方案，则返回 -1
return amt == 0 ? count : -1;
}
```
=== "Zig"

45
chapter_hashing/hash_algorithm.md
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@ -115,7 +115,6 @@ index = hash(key) % capacity
int hash = 0;
const int MODULUS = 1000000007;
for (unsigned char c : key) {
cout << (int)c << endl;
hash ^= (int)c;
}
return hash & MODULUS;
@ -511,13 +510,47 @@ index = hash(key) % capacity
=== "C"
```c title="simple_hash.c"
[class]{}-[func]{addHash}
/* 加法哈希 */
int addHash(char *key) {
long long hash = 0;
const int MODULUS = 1000000007;
for (int i = 0; i < strlen(key); i++) {
hash = (hash + (unsigned char)key[i]) % MODULUS;
}
return (int)hash;
}
[class]{}-[func]{mulHash}
/* 乘法哈希 */
int mulHash(char *key) {
long long hash = 0;
const int MODULUS = 1000000007;
for (int i = 0; i < strlen(key); i++) {
hash = (31 * hash + (unsigned char)key[i]) % MODULUS;
}
return (int)hash;
}
[class]{}-[func]{xorHash}
/* 异或哈希 */
int xorHash(char *key) {
int hash = 0;
const int MODULUS = 1000000007;
[class]{}-[func]{rotHash}
for (int i = 0; i < strlen(key); i++) {
hash ^= (unsigned char)key[i];
}
return hash & MODULUS;
}
/* 旋转哈希 */
int rotHash(char *key) {
long long hash = 0;
const int MODULUS = 1000000007;
for (int i = 0; i < strlen(key); i++) {
hash = ((hash << 4) ^ (hash >> 28) ^ (unsigned char)key[i]) % MODULUS;
}
return (int)hash;
}
```
=== "Zig"
@ -789,7 +822,7 @@ $$
=== "C"
```c title="built_in_hash.c"
// C 未提供内置 hash code 函数
```
=== "Zig"

2
chapter_heap/build_heap.md
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@ -176,7 +176,7 @@ comments: true
maxHeap *h = (maxHeap *)malloc(sizeof(maxHeap));
h->size = size;
memcpy(h->data, nums, size * sizeof(int));
for (int i = parent(size - 1); i >= 0; i--) {
for (int i = parent(h, size - 1); i >= 0; i--) {
// 堆化除叶节点以外的其他所有节点
siftDown(h, i);
}

26
chapter_searching/binary_search_edge.md
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@ -181,7 +181,17 @@ status: new
=== "C"
```c title="binary_search_edge.c"
[class]{}-[func]{binarySearchLeftEdge}
/* 二分查找最左一个 target */
int binarySearchLeftEdge(int *nums, int numSize, int target) {
// 等价于查找 target 的插入点
int i = binarySearchInsertion(nums, numSize, target);
// 未找到 target ，返回 -1
if (i == numSize || nums[i] != target) {
return -1;
}
// 找到 target ，返回索引 i
return i;
}
```
=== "Zig"
@ -389,7 +399,19 @@ status: new
=== "C"
```c title="binary_search_edge.c"
[class]{}-[func]{binarySearchRightEdge}
/* 二分查找最右一个 target */
int binarySearchRightEdge(int *nums, int numSize, int target) {
// 转化为查找最左一个 target + 1
int i = binarySearchInsertion(nums, numSize, target + 1);
// j 指向最右一个 target ，i 指向首个大于 target 的元素
int j = i - 1;
// 未找到 target ，返回 -1
if (j == -1 || nums[j] != target) {
return -1;
}
// 找到 target ，返回索引 j
return j;
}
```
=== "Zig"

34
chapter_searching/binary_search_insertion.md
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@ -249,7 +249,22 @@ status: new
=== "C"
```c title="binary_search_insertion.c"
[class]{}-[func]{binarySearchInsertionSimple}
/* 二分查找插入点（无重复元素） */
int binarySearchInsertionSimple(int *nums, int numSize, int target) {
int i = 0, j = numSize - 1; // 初始化双闭区间 [0, n-1]
while (i <= j) {
int m = i + (j - i) / 2; // 计算中点索引 m
if (nums[m] < target) {
i = m + 1; // target 在区间 [m+1, j] 中
} else if (nums[m] > target) {
j = m - 1; // target 在区间 [i, m-1] 中
} else {
return m; // 找到 target ，返回插入点 m
}
}
// 未找到 target ，返回插入点 i
return i;
}
```
=== "Zig"
@ -531,7 +546,22 @@ status: new
=== "C"
```c title="binary_search_insertion.c"
[class]{}-[func]{binarySearchInsertion}
/* 二分查找插入点（存在重复元素） */
int binarySearchInsertion(int *nums, int numSize, int target) {
int i = 0, j = numSize - 1; // 初始化双闭区间 [0, n-1]
while (i <= j) {
int m = i + (j - i) / 2; // 计算中点索引 m
if (nums[m] < target) {
i = m + 1; // target 在区间 [m+1, j] 中
} else if (nums[m] > target) {
j = m - 1; // target 在区间 [i, m-1] 中
} else {
j = m - 1; // 首个小于 target 的元素在区间 [i, m-1] 中
}
}
// 返回插入点 i
return i;
}
```
=== "Zig"