Acwing-----算法基础课之第二讲
831. KMP字符串
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链接:https://www.acwing.com/problem/content/833/
\(next[i] = j\) 代表 \(p[i, j] = p[i - j + 1, j]\)
#include <iostream>
using namespace std;
const int N = 10010, M = 100010;
int n, m;
char s[M], p[N];
int ne[N];
int main() {
cin >> n >> p + 1 >> m >> s + 1;
for (int i = 2, j = 0; i <= n; ++i) {
while (j && p[i] != p[j + 1]) j = ne[j];
if (p[i] == p[j + 1]) ++j;
ne[i] = j;
}
for (int i = 1, j = 0; i <= m; ++i) {
while (j && s[i] != p[j + 1]) j = ne[j];
if (s[i] == p[j + 1]) ++j;
if (j == n) {
cout << i - n << " ";
j = ne[j];
}
}
return 0;
}
835. Trie字符串统计
#include <iostream>
using namespace std;
const int N = 100010;
int son[N][26], cnt[N], idx, n;
char str[N];
void insert(char* str) {
int p = 0;
for (int i = 0; str[i]; ++i) {
int u = str[i] - 'a';
if (!son[p][u]) son[p][u] = ++idx;
p = son[p][u];
}
cnt[p]++;
}
int query(char* str) {
int p = 0;
for (int i = 0; str[i]; ++i) {
int u = str[i] - 'a';
if (!son[p][u]) return 0;
p = son[p][u];
}
return cnt[p];
}
int main() {
cin >> n;
while (n--) {
char op[2];
scanf("%s%s", &op, &str);
if (*op == 'I') insert(str);
else cout << query(str) << endl;
}
return 0;
}
836. 合并集合
#include <iostream>
using namespace std;
const int N = 100010;
int n, m;
int p[N];
int find(int x) {
if (p[x] != x) p[x] = find(p[x]);
return p[x];
}
int main() {
scanf("%d%d", &n, &m);
for (int i = 1; i <= n; ++i) p[i] = i;
while (m--) {
char op[2];
int a, b;
scanf("%s%d%d", op, &a, &b);
if (op[0] == 'M') p[find(a)] = find(b);
else {
if (find(a) == find(b)) puts("Yes");
else puts("No");
}
}
return 0;
}
838. 堆排序
#include <iostream>
#include <algorithm>
using namespace std;
const int N = 100010;
int n, m;
int h[N], sz;
void down(int u) {
int t = u;
if (u * 2 <= sz && h[u * 2] < h[t]) t = u * 2;
if (u * 2 + 1 <= sz && h[u * 2 + 1] < h[t]) t = u * 2 + 1;
if (u != t) {
swap(h[u], h[t]);
down(t);
}
}
int main() {
scanf("%d%d", &n, &m);
for (int i = 1; i <= n; ++i) scanf("%d", &h[i]);
sz = n;
for (int i = n / 2; i ; --i) down(i);
while (m--) {
printf("%d ", h[1]);
h[1] = h[sz];
sz--;
down(1);
}
return 0;
}