Codeforces Round #556 (Div. 2)

比赛链接

A

贪心

#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <queue>
#include <vector>
#include <set>
using namespace std;
const int N = 1005;
int a[N], b[N];
int n, m, bou, res;
inline bool rule(int x, int y){
	return x > y;
}
int main(){
	scanf("%d%d%d", &n, &m, &bou);
	for(int i = 1; i <= n; ++i) scanf("%d", &a[i]);
	for(int i = 1; i <= m; ++i) scanf("%d", &b[i]);
	sort(a + 1, a + n + 1); sort(b + 1, b + m + 1, rule);
	int cnt = b[1] > a[1] ? bou / a[1] : 0;
	res = cnt * b[1] - cnt * a[1] + bou; 
	printf("%d", res);
	return 0;
}

B

贪心。。

#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <queue>
#include <vector>
#include <set>
using namespace std;
const int N = 55;
int n;
bool map[N][N], col[N][N];
inline void print(int x, int y){
	if(!(map[x][y] & map[x + 1][y] & map[x + 1][y - 1]
	 & map[x + 1][y + 1] & map[x + 2][y])){
		printf("NO
"); exit(0);
	}
    map[x][y] = map[x + 1][y] = map[x + 1][y - 1]
	= map[x + 1][y + 1] = map[x + 2][y] = 0;
}
int main(){
	scanf("%d", &n);
	char str[N];
	for(int i = 1; i <= n; ++i){
		scanf("%s", str + 1);
		for(int j = 1; j <= n; ++j){
			map[i][j] = (str[j] == '.');
		}
	}
	for(int i = 1; i <= n; ++i){
		for(int j = 1; j <= n; ++j){
			if(map[i][j]) print(i, j);
		}
	}
	printf("YES
");
	return 0;
}

C

贪心？？。。。
先放2 再放1 再放所有2 再放所有1

#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <queue>
#include <vector>
#include <set>
using namespace std;
int n, cnt1, cnt2;
int main(){
	scanf("%d", &n);
	for(int i = 1, x; i <= n; ++i){
		scanf("%d", &x);
		if(x == 1) ++cnt1; else ++cnt2;
	}
	if(cnt1 == 0){
		for(int i = 1; i <= cnt2; ++i) putchar('2'), putchar(' ');
		return 0;
	}
	if(cnt2 == 0){
		for(int i = 1; i <= cnt1; ++i) putchar('1'), putchar(' ');
		return 0; 
	}
	putchar('2'), putchar(' '), putchar('1'), putchar(' ');
	for(int i = 2; i <= cnt2; ++i) putchar('2'), putchar(' ');
	for(int i = 2; i <= cnt1; ++i) putchar('1'), putchar(' ');   
	return 0;
}

D

动态规划

#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <queue>
#include <vector>
#include <set>
#define id(x) (x - 'a')
using namespace std;
const int N = 1e5 + 5;
const int M = 255;
const int Sig = 55;
const int inf = 0x3f3f3f3f;
int n, m;
char str[N];
int p[N][Sig], pre[Sig];
int f[M][M][M];
int ss[3][M], top[3];

inline void ins(int type){
	int ii, jj, kk; ii = jj = kk = 0;
	if(type == 0) ii = top[0];
	else if(type == 1) jj = top[1];
	else kk = top[2]; 
	for(int i = ii; i <= top[0]; ++i){
		for(int j = jj; j <= top[1]; ++j){
			for(int k = kk; k <= top[2]; ++k){
				if(i && f[i - 1][j][k] < inf) f[i][j][k] = min(f[i][j][k], p[f[i - 1][j][k]][ss[0][i]]);
				if(j && f[i][j - 1][k] < inf) f[i][j][k] = min(f[i][j][k], p[f[i][j - 1][k]][ss[1][j]]);
				if(k && f[i][j][k - 1] < inf) f[i][j][k] = min(f[i][j][k], p[f[i][j][k - 1]][ss[2][k]]);
			    //printf("%d %d %d %d
", i, j, k, f[i][j][k]);
			}
		}
	}
}

inline void del(int type){
	int ii, jj, kk; ii = jj = kk = 0;
	if(type == 0) ii = top[0];
	else if(type == 1) jj = top[1];
	else kk = top[2]; 
	for(int i = ii; i <= top[0]; ++i)
		for(int j = jj; j <= top[1]; ++j)
			for(int k = kk; k <= top[2]; ++k)
				f[i][j][k] = inf;
} 

int main(){ 
    scanf("%d%d%s", &n, &m, str + 1);
    
    for(int i = 0; i < Sig; ++i) pre[i] = inf;
	for(int i = n; i >= 1; --i){
		for(int j = 0; j < Sig; ++j) p[i][j] = pre[j];
		pre[id(str[i])] = i;
	}  
	for(int j = 0; j < Sig; ++j) p[0][j] = pre[j];
	 
	memset(f, 0x3f, sizeof(f)); f[0][0][0] = 0;
	char opt[5], rd[5]; int x, y;
	while(m--){
		scanf("%s%d", opt, &x); --x;
		if(opt[0] == '+'){
			scanf("%s", rd); y = id(rd[0]);
			ss[x][++top[x]] = y;
			ins(x);
		}
		else {
			del(x);
			--top[x];
		}
		//printf("%d %d %d %d
", top[0], top[1], top[2], f[top[0]][top[1]][top[2]]);
		if(f[top[0]][top[1]][top[2]] <= n) printf("YES
");
		else printf("NO
");
	}	
	return 0;
}

E

(题目链接)[http://codeforces.com/contest/1150/problem/E]
跪求这道题！！！qvq有会的大佬麻烦救救孩子！！！
感恩戴德！
qq3338315493