[备份]算法模板大集锦
一、介绍
这是一篇赶工赶出来并且随时会更新的备份文章，里面汇集了我曾学过的所有高级（也就是太长了我记不住）算法的模板。大部分直接从以前的文章里蒯过来，所以对于任意一份模板，都说不定将来再次翻阅的时候忍受不了当时的格式/命名/写法等等而进行修改。
二、目录
1、网络流Dinic算法
2、Tarjan算法
3、倍增LCA
4、AC自动机
5、主席树
6、BKDRHash
三、正文
1、网络流Dinic算法
1 #include <cstdio> 2 #include <cstring> 3 4 #define MAXN 205 5 #define MAXM 205 6 #define INF 0x3f3f3f3f 7 8 int m, n, u, v, f, q[MAXN * MAXN], h[MAXN], d[MAXN], o = 1, ans; 9 10 struct Edge { 11 int v, next, f; 12 } e[MAXM << 1]; 13 14 int min(int a, int b) { 15 return a < b ? a : b; 16 } 17 18 void add(int u, int v, int f) { 19 o++, e[o] = (Edge) {v, h[u], f}, h[u] = o; 20 } 21 22 bool BFS() { 23 int head = 1, tail = 2; 24 q[1] = 1, d[1] = 1; 25 while (head != tail) { 26 int o = q[head]; 27 for (int x = h[o]; x; x = e[x].next) { 28 int v = e[x].v; 29 if (!d[v] && e[x].f > 0) d[v] = d[o] + 1, q[tail++] = v; 30 } 31 head++; 32 } 33 return d[n] != 0; 34 } 35 36 int DFS(int o, int mif) { 37 int res = 0; 38 if (mif <= 0 || o == n) return mif; 39 for (int x = h[o]; x; x = e[x].next) { 40 int v = e[x].v; 41 if (d[v] == d[o] + 1) { 42 int of = DFS(v, min(mif, e[x].f)); 43 e[x].f -= of, e[x ^ 1].f += of, mif -= of, res += of; 44 if (!mif) break; 45 } 46 } 47 return res; 48 } 49 50 int main() { 51 scanf("%d %d", &m, &n); 52 for (int i = 1; i <= m; i++) scanf("%d %d %d", &u, &v, &f), add(u, v, f), add(v, u, 0); 53 while (BFS()) ans += DFS(1, INF), memset(d, 0, sizeof(d)); 54 printf("%d", ans); 55 return 0; 56 }
2、Tarjan算法
1 #include <cstdio> 2 3 #define MAXN 500005 4 #define MAXM 500005 5 6 int n, m, u[MAXN], v[MAXN], tw[MAXN], ts, p, to, tb[MAXN], th[MAXN]; 7 int w[MAXN], b[MAXN], s, h[MAXN], o, lik[MAXN]; 8 int dfn[MAXN], low[MAXN], ins[MAXN], st[MAXN], tot, t, tim; 9 int f[MAXN], ans; 10 11 struct Edge { 12 int v, next; 13 } e[MAXM], te[MAXM]; 14 15 int min(int a, int b) { 16 return a < b ? a : b; 17 } 18 19 int max(int a, int b) { 20 return a > b ? a : b; 21 } 22 23 void add(int u, int v, int t) { 24 if (t) to++, te[to] = (Edge) {v, th[u]}, th[u] = to; 25 else o++, e[o] = (Edge) {v, h[u]}, h[u] = o; 26 } 27 28 void init() { 29 scanf("%d %d", &n, &m); 30 for (int i = 1; i <= m; i++) scanf("%d %d", &u[i], &v[i]), add(u[i], v[i], 1); 31 for (int i = 1; i <= n; i++) scanf("%d", &tw[i]); 32 scanf("%d %d", &ts, &p); 33 for (int i = 1; i <= p; i++) scanf("%d", &o), tb[o] = 1; 34 } 35 36 void tarjan(int o) { 37 dfn[o] = low[o] = ++tim, ins[o] = 1, st[++t] = o; 38 for (int x = th[o]; x; x = te[x].next) { 39 int v = te[x].v; 40 if (!dfn[v]) tarjan(v), low[o] = min(low[v], low[o]); 41 else if (ins[v] && dfn[v] < low[o]) low[o] = dfn[v]; 42 } 43 if (dfn[o] == low[o]) { 44 int x; tot++; 45 do x = st[t--], ins[x] = 0, lik[x] = tot; while (x != o); 46 } 47 } 48 49 void rebuild() { 50 for (int i = 1; i <= m; i++) if (lik[u[i]] != lik[v[i]]) add(lik[u[i]], lik[v[i]], 0); 51 for (int i = 1; i <= n; i++) { 52 w[lik[i]] += tw[i]; 53 if (i == ts) s = lik[i]; 54 if (tb[i]) b[lik[i]] = 1; 55 } 56 f[s] = w[s]; 57 } 58 59 void DFS(int o) { 60 if (b[o]) ans = max(ans, f[o]); 61 for (int x = h[o]; x; x = e[x].next) { 62 int v = e[x].v; 63 if (f[o] + w[v] > f[v]) f[v] = f[o] + w[v], DFS(v); 64 } 65 } 66 67 int main() { 68 init(); 69 for (int i = 1; i <= n; i++) if (!dfn[i]) tarjan(i); 70 rebuild(); 71 DFS(s); 72 printf("%d", ans); 73 return 0; 74 }
3、倍增LCA
1 void prep() { 2 for (int i = 1; i <= n; i++) p[i][0] = fa[i]; 3 for (int j = 1; (1 << j) <= n; j++) 4 for (int i = 1; i <= n; i++) 5 if (p[i][j - 1]) p[i][j] = p[p[i][j - 1]][j - 1]; 6 } 7 8 int lca_h() { 9 if (d[x] < d[y]) swap(x, y); 10 while (d[x] != d[y]) { 11 int o = 1; 12 while (d[p[x][o]] > d[y]) o++; 13 x = p[x][o - 1]; 14 } 15 while (x != y) { 16 int o = 1; 17 while (p[x][o] != p[y][o]) o++; 18 x = p[x][o - 1], y = p[y][o - 1]; 19 } 20 return x; 21 }
4、AC自动机
1 #include <cstdio> 2 #include <cstring> 3 4 #define MAXM 1000005 5 6 int T, n, tot, q[MAXM], ls, l, r; 7 char s[55], ch[MAXM]; 8 9 struct Tree { 10 int a[26], x, f; 11 } t[MAXM]; 12 13 void insert() { 14 int o = r; 15 for (int i = 0; i < ls; i++) { 16 int x = s[i] - 'a'; 17 if (!t[o].a[x]) t[o].a[x] = ++tot; 18 o = t[o].a[x]; 19 } 20 t[o].x++; 21 } 22 23 void getf() { 24 int head = 1, tail = 2; 25 q[1] = r; 26 while (head != tail) { 27 int o = q[head]; 28 for (int i = 0; i <= 25; i++) { 29 int v = t[o].a[i]; 30 if (!v) continue; 31 if (o == r) t[v].f = r; 32 else { 33 int of = t[o].f; 34 while (of) { 35 if (t[of].a[i]) { 36 t[v].f = t[of].a[i]; 37 break; 38 } 39 of = t[of].f; 40 } 41 if (!of) t[v].f = r; 42 } 43 q[tail++] = v; 44 } 45 head++; 46 } 47 } 48 49 int find() { 50 int ans = 0, x = r; 51 for (int i = 0; i < l; i++) { 52 int o = ch[i] - 'a'; 53 while (!t[x].a[o] && x != r) x = t[x].f; 54 x = t[x].a[o] ? t[x].a[o] : r; 55 int y = x; 56 while (t[y].x) ans += t[y].x, t[y].x = 0, y = t[y].f; 57 } 58 return ans; 59 } 60 61 int main() { 62 scanf("%d", &T); 63 for (int i = 1; i <= T; i++) { 64 scanf("%d", &n), r = ++tot; 65 for (int j = 1; j <= n; j++) scanf("%s", s), ls = strlen(s), insert(); 66 getf(); 67 for (int j = r + 1; j <= tot; j++) if (!t[j].f) t[j].f = r; 68 scanf("%s", ch), l = strlen(ch); 69 printf("%d\n", find()); 70 } 71 return 0; 72 }
5、主席树
1 #include <cstdio> 2 #include <algorithm> 3 using namespace std; 4 5 #define MAXN 100005 6 7 int T, n, m, l, r, k, tot, root[MAXN], b[MAXN], lik[MAXN]; 8 9 struct num { 10 int w, n, r; 11 } a[MAXN]; 12 13 struct cmpw { 14 bool operator () (num a, num b) { 15 return a.w < b.w; 16 } 17 } cw; 18 19 struct cmpn { 20 bool operator () (num a, num b) { 21 return a.n < b.n; 22 } 23 } cn; 24 25 struct Tree { 26 int l, r, w; 27 } t[MAXN * 20]; 28 29 void chg() { 30 sort(a + 1, a + n + 1, cw); 31 for (int i = 1; i <= n; i++) a[i].r = i; 32 sort(a + 1, a + n + 1, cn); 33 for (int i = 1; i <= n; i++) b[i] = a[i].r, lik[b[i]] = a[i].w; 34 } 35 36 void build(int o, int l, int r, int w, int x) { 37 t[o] = t[x], t[o].w++; 38 if (l == r) return; 39 int m = (l + r) >> 1; 40 if (w <= m) build(t[o].l = ++tot, l, m, w, t[x].l); 41 else build(t[o].r = ++tot, m + 1, r, w, t[x].r); 42 } 43 44 int query(int rl, int rr, int l, int r, int k) { 45 if (l == r) return l; 46 int w = t[t[rr].l].w - t[t[rl].l].w, m = (l + r) >> 1; 47 return w >= k ? query(t[rl].l, t[rr].l, l, m, k) : query(t[rl].r, t[rr].r, m + 1, r, k - w); 48 } 49 50 int main() { 51 scanf("%d", &T); 52 for (int j = 1; j <= T; j++) { 53 root[0] = 0, tot = 0; 54 scanf("%d %d", &n, &m); 55 for (int i = 1; i <= n; i++) scanf("%d", &a[i].w), a[i].n = i; 56 chg(); 57 for (int i = 1; i <= n; i++) 58 build(root[i] = ++tot, 1, n, b[i], root[i - 1]); 59 for (int i = 1; i <= m; i++) { 60 scanf("%d %d %d", &l, &r, &k); 61 printf("%d\n", lik[query(root[l - 1], root[r], 1, n, k)]); 62 } 63 } 64 return 0; 65 }
6、BKDRHash
1 #define x 131 2 #define MOD 1000000007 3 int h[MAXN]; char a[MAXN]; 4 void getHash() { 5 int len = strlen(a); 6 for (int i = 0; i <= len - 1; i++) h[i] = (h[i - 1] * x + a[i]) % MOD; 7 }
