【BZOJ 3790】 神奇項鏈
阿新 • • 發佈:2018-07-01
clu UC IV std using har www oid code
【題目鏈接】
https://www.lydsy.com/JudgeOnline/problem.php?id=3790
【算法】
manacher + 貪心
【代碼】
#include<bits/stdc++.h> using namespace std; #define MAXN 500010 char s[MAXN]; struct info { int l,r; }; inline bool cmp(info a,info b) { return a.l != b.l ? a.l < b.l : a.r > b.r; } inlinevoid Manacher() { int i,len,pos = 0,mx = 0,n = 0,ans,r; static int p[MAXN<<1]; static char tmp[MAXN<<1]; static info a[MAXN<<1]; len = strlen(s+1); for (i = 1; i <= len; i++) { tmp[2*i-1] = ‘#‘; tmp[2*i] = s[i]; } tmp[len = 2 * len + 1] = ‘#‘; for (i = 1; i <= len; i++) { if (mx > i) p[i] = min(p[2*pos-i],mx-i); else p[i] = 1; while (i - p[i] >= 1 && i + p[i] <= len && tmp[i-p[i]] == tmp[i+p[i]]) p[i]++;if (i + p[i] - 1 > mx) { mx = i + p[i] - 1; pos = i; } } for (i = 1; i <= len; i++) a[++n] = (info){i-p[i]+1,i+p[i]-1}; sort(a+1,a+n+1,cmp); r = a[1].r; ans = 1; pos = 2; while (r < len) { mx = r; while (pos <= n && a[pos].l <= r + 1) { mx = max(mx,a[pos].r); pos++; } ans++; r = mx; } printf("%d\n",ans-1); } int main() { while (scanf("%s",s+1) != EOF) Manacher(); return 0; }
【BZOJ 3790】 神奇項鏈