11.4 problem solving report of Simulation Competition

Background:

Hearing Szt && BS' English is poor last night.

So I try writting this in English this time. /xyx

Examination process:

7:30 hand out test questions

7:45 Finish T1

8:20 Finish T2

8:30 ~ 9:00 Begin to do T3

9:30 Be sure I can't finish T3

9:00 ~ 11:00 Play very happily /cy

Dream: pts：100 + 100 + 0 = 200

True: pts: 100 + 40 + 0 = 40

ahh Why My T2 Hang up ??

T1 buy book

solution

Easy problem!!

Simulated topic meaning.

Only notice: When you encounter 20, first consider using 10.

Time: (O(n))

code

#include<bits/stdc++.h>
using namespace std;
int read() {
  int x = 0, f = 1; char c = getchar();
  while(c < '0' || c > '9') {if(c == '-') f = -1;c = getchar();}
  while(c >= '0' && c <= '9') {x = x * 10 + c - '0';c = getchar();}
  return x * f;
}
int n, cnt[5];
int main() {
  //freopen("book.in", "r", stdin);
  //freopen("book.out", "w", stdout);
  n = read();
  for (int i = 1; i <= n; i++) {
  	int x = read();
  	if(i == 1 && x > 5) {puts("NO"); return 0;}
  	if(x == 5) cnt[1]++;	 
	else if(x == 10) {
	  if(!cnt[1]) {puts("NO"); return 0;}
	  cnt[1]--, cnt[2]++;
	}
    else if(x == 20) {
      if(!cnt[1]) {puts("NO"); return 0;}
      cnt[1]--;
      if(cnt[2]) cnt[2]--, cnt[3]++;
	  else {
	  	if(cnt[1] < 2) {puts("NO"); return 0;}
	  	cnt[1] -= 2, cnt[3]++;
	  }
    }
  }
  puts("YES");
  return 0;
}

T2 program

solution

Using a stack to do this from tail to head.

This problem will become very easy !!

I didn't take care of the details, So I hang up 60pts

Time: (O(n))

code

#include<bits/stdc++.h>
using namespace std;
const int MAXN = 1e6 + 5;
int read() {
  int x = 0, f = 1; char c = getchar();
  while(c < '0' || c > '9') {if(c == '-') f = -1;c = getchar();}
  while(c >= '0' && c <= '9') {x = x * 10 + c - '0';c = getchar();}
  return x * f;
}
int n, m, st[MAXN], a[MAXN], tp, pos[MAXN];
int main() {
  //freopen("program.in", "r", stdin);
  //freopen("program.out", "w", stdout);
  n = read();
  for (int i = 1; i <= n; i++) a[i] = read();
  m = read();
  for (int i = 1, x; i <= m; i++) {
    x = read(); 
    if(a[x] > 0) a[x] = -a[x];  	
  }
  st[++tp] = a[n], pos[tp] = n;
  for (int i = n - 1; i >= 1; i--) {
  	 if(a[i] < 0) st[++tp] = a[i], pos[tp] = i;
  	 else {
  	   if(abs(st[tp]) == a[i]) {
		  if(a[pos[tp]] > 0) a[pos[tp]] = -a[pos[tp]]; 
		  tp--;
		}
	   else st[++tp] = a[i], pos[tp] = i;
	 }
  }
  if(tp) puts("NO");
  else {
  	for (int i = 1; i <= n; i++) {
  	  if(a[i] > 0) printf("+%d ", a[i]);
	  else printf("%d ", a[i]);	
	}
  }
  return 0;
}

T3 maze

solution

Bracket match on figure

code

#include<bits/stdc++.h>
using namespace std;
const int MAXN = 110;
const int MAXM = 50010;
int read() {
  int x = 0, f = 1; char c = getchar();
  while(c < '0' || c > '9') {if(c == '-') f = -1;c = getchar();}
  while(c >= '0' && c <= '9') {x = x * 10 + c - '0';c = getchar();}
  return x * f;
}
int n, m, T;
struct node{int u, v, w;};
queue<node> q;
bool f[110][110][21];
void Init() {
   for (int i = 1, u, v, w; i <= m; i++) {
  	u = read(), v = read(), w = read();
  	if(!w) {
  	  f[u][v][w] = f[v][u][w] = true;
  	  q.push((node){u, v, w}), q.push((node){v, u, w});
	}
	else if (w < 0) {
	  w = -w;
	  f[u][v][w] = f[v][u][w] = true; 
	}
	else {
	   w += 10;
	   f[u][v][w] = f[v][u][w] = true;
	   q.push((node){u, v, w}), q.push((node){v, u, w});
	}
  }
}
void Update() {
  while(!q.empty()) {
  	 int u = q.front().u, v = q.front().v, w = q.front().w;
  	 q.pop();
	 if(!w) {
  	  for (int i = 1; i <= n; i++) {
  	     if (f[i][u][0] && !f[i][v][0]) {
  	        f[i][v][0] = 1;
			q.push((node){i, v, 0});	 
		  }
		  if(f[v][i][0] && !f[u][i][0]) {
		  	 f[u][i][0] = 1;
		  	 q.push((node){u, i, 0});
		  }	
		  for (int j = 11; j <= 20; j++) {
		  	 if (f[i][u][j] && !f[i][v][j]) {
		  	   f[i][v][j] = 1;
			   q.push((node){i, v, j});	 
			 }
		  }
	   }	
	 }
	 else {
	    for (int i = 1; i <= n; i++) {
	      if(f[v][i][w - 10] && !f[u][i][0]) {
	      	f[u][i][0] = 1;
	      	q.push((node){u, i, 0});
		  }
		}
	 }
  }
}
int main() {
  n = read(), m = read();
  for (int i = 1; i <= n; i++) f[i][i][0] = 1;
  Init();
  Update();
  T = read();
  for (int i = 1, u, v; i <= T; i++){
    u = read(), v = read();
    puts(f[u][v][0] ? "YES" : "NO");
  }
  return 0;
}