Good Bye 2014 A B C D E
发布时间:2020-12-13 20:11:45 所属栏目:PHP教程 来源:网络整理
导读:A:签到,从左往右走1遍判断下有无遇到t便可 B:先利用floyd求出传递闭包,然后利用这个传递闭包贪心小的尽可能往前放便可 C:贪心的策略,放的顺序其实根据拿的顺序就能够肯定的,所以只要在拿的顺序上从左往右扫1遍便可 D:先DFS预处理出每条边两边点的个
A:签到,从左往右走1遍判断下有无遇到t便可
B:先利用floyd求出传递闭包,然后利用这个传递闭包贪心小的尽可能往前放便可
C:贪心的策略,放的顺序其实根据拿的顺序就能够肯定的,所以只要在拿的顺序上从左往右扫1遍便可
D:先DFS预处理出每条边两边点的个数,然后3元组对每一个边经过都是n - 2次,所以1个边都会被计算到n - 2 * 1边点 * 另外一边点个数
E:问题可以转化为查询每一个区间,未被覆盖的长度,那末利用线段树+离线处理,从右往左不断添加区间并查询便可
代码: #include <cstdio>
#include <cstdlib>
const int N = 30005;
int n,t,a[N];
int main() {
scanf("%d%d",&n,&t);
for (int i = 1; i <= n - 1; i++)
scanf("%d",&a[i]);
int bo = 0;
for (int i = 1; i <= t;) {
if (i == t) {
bo = 1;
break;
}
i += a[i];
}
printf("%s
",bo ? "YES" : "NO");
return 0;
}
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 305;
int n,a[N],g[N][N],vis[N];
char str[N];
int main() {
scanf("%d",&n);
for (int i = 0; i < n; i++) scanf("%d",&a[i]);
for (int i = 0; i < n; i++) {
scanf("%s",str);
for (int j = 0; j < n; j++)
g[i][j] = str[j] - '0';
g[i][i] = 1;
}
for (int k = 0; k < n; k++) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
g[i][j] |= (g[i][k]&g[k][j]);
}
}
}
for (int i = 0; i < n; i++) {
int Min = n;
for (int j = 0; j < n; j++) {
if (g[j][i] && !vis[a[j]]) {
Min = min(Min,a[j]);
}
}
vis[Min] = 1;
printf("%d ",Min);
}
return 0;
} #include <cstdio>
#include <cstring>
const int N = 505;
typedef long long ll;
int n,m,w[N],vis[N][N];
int v;
ll sum = 0;
int main() {
scanf("%d%d",&m);
for (int i = 1; i <= n; i++)
scanf("%d",&w[i]);
for (int i = 1; i <= m; i++) {
scanf("%d",&v);
for (int j = 1; j <= n; j++)
sum += w[j] * vis[v][j];
memset(vis[v],sizeof(vis[v]));
for (int j = 1; j <= n; j++) {
if (v == j) continue;
vis[j][v] = 1;
}
}
printf("%lld
",sum);
return 0;
} #include <cstdio>
#include <cstring>
#include <vector>
using namespace std;
const int N = 100005;
int n;
struct Edge {
int u,v,id,num;
double len;
Edge(){}
Edge(int u,int v,int id) {
this->u = u;
this->v = v;
this->id = id;
}
} e[N];
vector<Edge> g[N];
int dfs(int u,int p) {
int sz = 1;
for (int i = 0; i < g[u].size(); i++) {
int v = g[u][i].v;
if (v == p) continue;
int tmp = dfs(v,u);
sz += tmp;
e[g[u][i].id].num = tmp;
}
return sz;
}
int main() {
scanf("%d",&n);
int u,v;
double w;
for (int i = 1; i <= n - 1; i++) {
scanf("%d%d%lf",&u,&v,&w);
e[i].len = w;
g[u].push_back(Edge(u,i));
g[v].push_back(Edge(v,u,i));
}
dfs(1,0);
int q;
scanf("%d",&q);
int id,vv;
double sum = 0;
for (int i = 1; i <= n - 1; i++) {
sum += (double)(n - 2) * (e[i].num) * (n - e[i].num) * (e[i].len);
}
double c1 = (double)n * (n - 1) * (n - 2) / 2 / 3;
while (q--) {
scanf("%d%d",&id,&vv);
sum -= (double)(n - 2) * (e[id].num) * (n - e[id].num) * (e[id].len - vv);
e[id].len = vv;
printf("%.10lf
",sum / c1);
}
return 0;
} #include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int N = 200005;
struct query {
int l,r,id;
} s[N],q[N];
int n,ans[N];
bool cmp(query a,query b) {
return a.l > b.l;
}
int hash[N * 2],hn;
int find(int x) {
return lower_bound(hash,hash + hn,x) - hash;
}
#define lson(x) ((x<<1)+1)
#define rson(x) ((x<<1)+2)
struct Node {
int l,len,lazy;
void gao() {
lazy = 1;
len = 0;
}
} node[N * 8];
void pushup(int x) {
node[x].len = node[lson(x)].len + node[rson(x)].len;
}
void pushdown(int x) {
if (node[x].lazy) {
node[x].lazy = 0;
node[lson(x)].gao();
node[rson(x)].gao();
}
}
void build(int l,int r,int x = 0) {
node[x].l = l; node[x].r = r; node[x].lazy = 0;
if (l == r) {
node[x].len = hash[r + 1] - hash[l];
return;
}
int mid = (l + r) / 2;
build(l,mid,lson(x));
build(mid + 1,rson(x));
pushup(x);
}
void add(int l,int x = 0) {
if (node[x].l >= l && node[x].r <= r) {
node[x].gao();
return;
}
pushdown(x);
int mid = (node[x].l + node[x].r) / 2;
if (l <= mid) add(l,lson(x));
if (r > mid) add(l,rson(x));
pushup(x);
}
int query(int l,int x = 0) {
if (node[x].l >= l && node[x].r <= r)
return node[x].len;
int mid = (node[x].l + node[x].r) / 2;
int ans = 0;
pushdown(x);
if (l <= mid) ans += query(l,lson(x));
if (r > mid) ans += query(l,rson(x));
pushup(x);
return ans;
}
int main() {
scanf("%d",&n);
hn = 0;
for (int i = 0; i < n; i++) {
scanf("%d%d",&s[i].l,&s[i].r);
s[i].r += s[i].l;
hash[hn++] = s[i].l;
hash[hn++] = s[i].r;
}
sort(hash,hash + hn);
hn = unique(hash,hash + hn) - hash;
build(0,hn - 2);
int qn;
scanf("%d",&qn);
for (int i = 0; i < qn; i++) {
scanf("%d%d",&q[i].l,&q[i].r);
q[i].l--;
q[i].r--;
q[i].l = s[q[i].l].l;
q[i].r = s[q[i].r].l;
q[i].id = i;
}
sort(q,q + qn,cmp);
int now = n - 1;
for (int i = 0; i < qn; i++) {
while (s[now].l >= q[i].l && now >= 0) {
add(find(s[now].l),find(s[now].r) - 1);
now--;
}
ans[q[i].id] = query(find(q[i].l),find(q[i].r) - 1);
}
for (int i = 0; i < qn; i++)
printf("%d
",ans[i]);
return 0;
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