Codeforces Round #265 (Div. 2)_html/css_WEB-ITnose

Codeforces Round #265 (Div. 2)

题目链接

A：把数字变换后比较一下几个不一样即可

B：连续2个以上0当作一次操作，开头的0和结尾的0可以忽略

C：贪心从末尾去构造，由于保证一开始是回文，所以保证修改后出现回文只可能为长度2或3的，这样的话判断复杂度就很小了

D：暴力枚举情况，然后判断

E：把操作逆过来处理出每个数字对应的位数和相应数字，然后在for一遍计算答案即可

代码：

A：

#include <cstdio>#include <cstring>int n, num[105], sb[105];char s[105];int main() {    scanf("%d", &amp;n);    scanf("%s", s);    for (int i = 0; i   <br> B：  <p></p>  <p> </p>  <pre name="code" class="sycode">#include <cstdio>#include <cstring>const int N = 1005;int n, num[N];int solve() {	int ans = 0;	int s = 0, e = n - 1;	while (num[s] == 0 &amp;&amp; s = 0) e--;	for (int i = s ; i   <br> C：  <p></p>  <p> </p>  <pre name="code" class="sycode">#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int N = 1005;int n, p;char str[N];bool solve(int u) {	if (u = 0 &amp;&amp; str[u] == str[u - 1]) return solve(u);		if (u - 2 &gt;= 0 &amp;&amp; str[u] == str[u - 2]) return solve(u);		return true;	}}int main() {	scanf("%d%d", &amp;n, &amp;p);	scanf("%s", str);	if (solve(n - 1)) printf("%s\n", str);	else printf("NO\n");	return 0;}</algorithm></cstring></cstdio>

D：

#include <cstdio>#include <cstring>#include <cmath>#include <algorithm>#include <iostream>#include <set>using namespace std;struct Point {	int v[3];	void read() {		for (int i = 0; i   <br> E：  <p></p>  <p> </p>  <pre name="code" class="sycode">#include <cstdio>#include <cstring>#include <cmath>#include <vector>using namespace std;typedef long long ll;const ll MOD = 1000000007;const int N = 100005;char str[N], sss[N];int n;ll pow_mod(ll x, ll k) {    ll ans = 1;    while (k) {        if (k&amp;1) ans = (ans * x) % MOD;        x = x * x % MOD;        k &gt;&gt;= 1;    }    return ans;}ll v[15], l[15];ll idx(char c) {    return c - '0';}struct State {    ll u;    vector<ll> v;    void init(char *str) {        int len = strlen(str);        u = idx(str[0]);        v.clear();        for (int i = 3; i = 0; i--) {        ll lt = 0, vt = 0;        for (int j = 0; j   <br>  <br>  <p></p> </ll></vector></cmath></cstring></cstdio>