2017 Mid Central Regional F.Orderly Class(大水题)
这两天刷了两道过去的原题,看看思维还是8太行。
这道题问给出两个字符串,要求只翻转一次,问有几种不同的方法使得a串变成b串
我一开始没看到只翻转一次,还以为是个计数 + 字符串dp大难题,心想当年的学长队伍真厉害啊能上去拿1血,结果仔细看了看发现是个水题,只转一次,那就记录最大相等的串,然后翻过来看相等不相等,然后向外向内拓展看有没有头 == 尾的情况就行了,水题一道,8多说
#include <bits/stdc++.h> using namespace std; #define limit (20000 + 5)//防止溢出 #define INF 0x3f3f3f3f #define inf 0x3f3f3f3f3f #define lowbit(i) i&(-i)//一步两步 #define EPS 1e-6 #define FASTIO ios::sync_with_stdio(false);cin.tie(0); #define ff(a) printf("%d\n",a ); #define pi(a,b) pair<a,b> #define rep(i, a, b) for(ll i = a; i <= b ; ++i) #define per(i, a, b) for(ll i = b ; i >= a ; --i) #define MOD 998244353 #define traverse(u) for(int i = head[u]; ~i ; i = edge[i].next) #define FOPEN freopen("C:\\Users\\tiany\\CLionProjects\\acm_01\\data.txt", "rt", stdin) #define FOUT freopen("C:\\Users\\tiany\\CLionProjects\\acm_01\\dabiao.txt", "wt", stdout) #define debug(x) cout<<x<<endl typedef long long ll; typedef unsigned long long ull; inline ll read(){ ll sign = 1, x = 0;char s = getchar(); while(s > '9' || s < '0' ){if(s == '-')sign = -1;s = getchar();} while(s >= '0' && s <= '9'){x = (x << 3) + (x << 1) + s - '0';s = getchar();} return x * sign; }//快读 void write(ll x){ if(x < 0) putchar('-'),x = -x; if(x / 10) write(x / 10); putchar(x % 10 + '0'); } int f[limit]; int ans = 1; string str,str1; void checkin(int l, int r){ ++l,--r; while (l < r){ if(str[l] == str[r])++ans, --r, ++l; else return; } } int n; void checkout(int l, int r){ --l,++r; while (l >= 1 && r <= n){ if(str[l] == str[r])++ans, ++r, --l; else return; } } int main() { #ifdef LOCAL FOPEN; #endif cin>>str>>str1; n = str.length(); str = ' ' + str; str1 = ' ' + str1; int l = -1, r = -1; rep(i ,1,n){ if(str[i] != str1[i]) { if(l == -1){ l = i; } r = max(i, 1ll * r); } } string fst; string scd; rep(i ,l,r){ fst += str[i]; scd += str1[i]; } reverse(scd.begin(), scd.end()); if(fst != scd)return 0 * puts("0"); checkin(l,r); checkout(l,r); write(ans); return 0; }
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