几道瞎搜题

P1514 引水入城

#include <cmath>
#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;

const int A = 5e2 + 11;
const int inf = 0x3f3f3f3f;
const int dx[4] = {0, 0, 1, -1};
const int dy[4] = {-1, 1, 0, 0};

inline int read() {
  char c = getchar();
  int x = 0, f = 1;
  for ( ; !isdigit(c); c = getchar()) if (c == '-') f = -1;
  for ( ; isdigit(c); c = getchar()) x = x * 10 + (c ^ 48);
  return x * f;
}

struct node { int x, y; };
struct llrr { int l, r; } c[A];
int n, m, sum, h[A][A], l[A][A], r[A][A], vis[A][A]; 

inline bool cmp(llrr a, llrr b) {
  return a.l != b.l ? a.l < b.l : a.r < b.r;
}

inline void bfs(int a[A][A], int sx, int sy, int v, int tag) {
  if (a[sx][sy]) return;
  queue <node> Q;
  Q.push((node){sx, sy});
  a[sx][sy] = v;
  while (!Q.empty()) {
    int x = Q.front().x, y = Q.front().y;
    Q.pop();
    for (int i = 0; i < 4; i++) {
      int bx = x + dx[i], by = y + dy[i];
      if (bx < 1 || bx > n || by < 1 || by > m || a[bx][by]) continue;
      if (!tag && h[bx][by] >= h[x][y]) continue;
      if (tag && h[bx][by] <= h[x][y]) continue;
      Q.push((node){bx, by});
      a[bx][by] = a[x][y];
    }
  }
}

int main() {
  n = read(), m = read();
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= m; j++) h[i][j] = read();
  for (int i = 1; i <= m; i++) bfs(vis, 1, i, 1, 0);
  for (int i = 1; i <= m; i++) if (!vis[n][i]) sum++;
  if (sum) return cout << "0\n" << sum << '\n', 0;
  for (int i = 1; i <= m; i++) if (!l[n][i]) bfs(l, n, i, i, 1);
  for (int i = m; i >= 1; i--) if (!r[n][i]) bfs(r, n, i, i, 1);
  for (int i = 1; i <= m; i++) {
    c[i].l = l[1][i], c[i].r = r[1][i];
  }
  sort(c + 1, c + 1 + m, cmp);
  int to = 0, now = 1, ans = 0;
  for (int i = 1; i <= m; i++) {
    if (now >= c[i].l) to = max(to, c[i].r);
    else ans++, now = to + 1, to = max(to, c[i].r);
  }
  if (now - 1 < m) ans++;
  cout << "1\n" << ans << '\n';
  return 0;
}

P1120 小木棍 ［数据加强版］

就使劲剪枝

#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;

const int A = 1e5 + 11;
const int B = 1e6 + 11;
const int mod = 1e9 + 7;
const int inf = 0x3f3f3f3f;

inline int read() {
  char c = getchar();
  int x = 0, f = 1;
  for ( ; !isdigit(c); c = getchar()) if (c == '-') f = -1;
  for ( ; isdigit(c); c = getchar()) x = x * 10 + (c ^ 48);
  return x * f;
}

int n, len, sum, maxn, tot, a[A], vis[A]; 

bool cmp(int a, int b) {
  return a > b;
}

bool dfs(int now, int lo, int last) {
  if (now == n + 1 && lo == len) return true;
  if (lo == len) lo = 0, last = 0;
  for (int i = last + 1; i <= tot; i++) {
    if (vis[i]) continue;
    if (a[i] + lo > len) continue;
    vis[i] = 1;
    if (dfs(now + 1, lo + a[i], i)) return true;
    vis[i] = 0;
    //if (lo == 0 || lo + a[i] == len) return false;
    while (a[i] == a[i + 1]) i++;
  }
  return false;
}

int main() {
  n = read();
  for (int i = 1; i <= n; i++) {
    int x = read();
    if (x <= 50) {
      a[++tot] = x;
      maxn = max(maxn, a[tot]);
      sum += a[tot];
    }
  }
  n = tot;
  stable_sort(a + 1, a + 1 + tot, cmp);
  for (len = maxn; len <= sum / 2; len++) {
    if (sum % len) continue;
    if (dfs(1, 0, 0)) {
      cout << len << '\n';
      return 0;
    }
  }
  cout << sum << '\n';
  return 0;
}

P1434 [SHOI2002]滑雪

直接乱搞

#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;

const int A = 1e3 + 11;
const int B = 1e6 + 11;
const int mod = 1e9 + 7;
const int inf = 0x3f3f3f3f;

inline int read() {
  char c = getchar();
  int x = 0, f = 1;
  for ( ; !isdigit(c); c = getchar()) if (c == '-') f = -1;
  for ( ; isdigit(c); c = getchar()) x = x * 10 + (c ^ 48);
  return x * f;
}

int n, m, ans;
int f[A][A], a[A][A];

int work(int x, int y) {
if (f[x][y] != 0) return f[x][y];
  int ans = 0;
  if (x - 1 > 0)
    if (a[x - 1][y] > a[x][y])
      ans = max(ans, work(x - 1, y));
  if (x + 1 > 0)
    if (a[x + 1][y] > a[x][y])
      ans = max(ans, work(x + 1, y));
  if (y - 1 > 0)
    if (a[x][y - 1] > a[x][y])
      ans = max(ans, work(x, y - 1));
  if (y + 1 > 0)
    if (a[x][y + 1] > a[x][y])
      ans = max(ans, work(x, y + 1));
  f[x][y] = ans + 1;
  return f[x][y];
}

int main() {
  n = read(), m = read();
  for (int i = 1; i <= n; i++)
    for (int j = 1; j <= m; j++)
      a[i][j] = read();
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++) {
      if (f[i][j] == 0)
        f[i][j] = work(i, j);
        ans = max(ans, f[i][j]);
      }
    }
  cout << ans << "\n";
  return 0;
}

P1074 靶形数独

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;

const int A = 5e5 + 11;
const int B = 1e6 + 11;
const int mod = 1e9 + 7;
const int inf = 0x3f3f3f3f;

inline int read() {
	char c = getchar();
	int x = 0, f = 1;
	for( ; !isdigit(c); c = getchar()) if(c == '-') f = -1;
	for( ; isdigit(c); c = getchar()) x = x * 10 + (c ^ 48);
	return x * f;
}

const int score[10][10] = {
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 6, 6, 6, 6, 6, 6, 6, 6, 6},
{0, 6, 7, 7, 7, 7, 7, 7, 7, 6},
{0, 6, 7, 8, 8, 8, 8, 8, 7, 6},
{0, 6, 7, 8, 9, 9, 9, 8, 7, 6},
{0, 6, 7, 8, 9,10, 9, 8, 7, 6},
{0, 6, 7, 8, 9, 9, 9, 8, 7, 6},
{0, 6, 7, 8, 8, 8, 8, 8, 7, 6},
{0, 6, 7, 7, 7, 7, 7, 7, 7, 6},
{0, 6, 6, 6, 6, 6, 6, 6, 6, 6}, };

int pd(int i, int j) {
	if(i <= 3 && j <= 3) return 1;
	if(i <= 3 && j <= 6) return 2;
	if(i <= 3 && j <= 9) return 3;
	if(i <= 6 && j <= 3) return 4;
	if(i <= 6 && j <= 6) return 5;
	if(i <= 6 && j <= 9) return 6;
	if(i <= 9 && j <= 3) return 7;
	if(i <= 9 && j <= 6) return 8;
	if(i <= 9 && j <= 9) return 9;
}

int a[11][11], hang[11][11], lie[11][11], sma[11][11];
int tot, ans = -1;
struct node { int sum, line; } qwq[11];

bool cmp(node a, node b) {
	return a.sum < b.sum;
}

void coun() {
	int now = 0;
	for(int i = 1; i <= 9; i++) 
		for(int j = 1; j <= 9; j++)
			now += a[i][j] * score[i][j];
	ans = max(ans, now);
	return;
}

void dfs(int cnt, int ho, int li) { //行、列、这一行填了多少个 
	if(cnt == 10) { coun(); return; }
	if(li == 10) dfs(cnt + 1, qwq[cnt + 1].line, 1);
	if(!a[ho][li]) {
		for(int i = 1; i <= 9; i++) {
			if(!hang[ho][i] && !lie[li][i] && !sma[pd(ho, li)][i]) {
				hang[ho][i] = lie[li][i] = sma[pd(ho, li)][i] = 1;
				a[ho][li] = i; dfs(cnt, ho, li + 1); a[ho][li] = 0;
				hang[ho][i] = lie[li][i] = sma[pd(ho, li)][i] = 0;
			}
		}
	}
	else dfs(cnt, ho, li + 1);
}

int main() {
	for(int i = 1; i <= 9; i++) {
		tot = 0;
		for(int j = 1; j <= 9; j++) {
			a[i][j] = read();
			if(a[i][j]) {
				sma[pd(i, j)][a[i][j]] = 1;
				hang[i][a[i][j]] = 1;
				lie[j][a[i][j]] = 1;
			}
			else tot++;
			qwq[i].line = i, qwq[i].sum = tot;
		}
	}
	sort(qwq + 1, qwq + 1 + 9, cmp);
	dfs(1, qwq[1].line, 1);
	cout << ans; return 0;
}