[CERC 2008] Suffix reconstruction
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[题目链接]
https://www.lydsy.com/JudgeOnline/problem.php?id=4319
[算法]
首先 , 我们可以求出这个字符串的rank数组
按照SA逐位枚举 , 贪心构造 , 即可
时间复杂度 : O(N)
[代码]
#include<bits/stdc++.h> using namespace std; typedef long long ll; typedef long double ld; typedef unsigned long long ull; const int N = 5e6 + 10; int n; int sa[N] , rk[N]; char s[N]; template <typename T> inline void chkmax(T &x,T y) { x = max(x,y); } template <typename T> inline void chkmin(T &x,T y) { x = min(x,y); } template <typename T> inline void read(T &x) { T f = 1; x = 0; char c = getchar(); for (; !isdigit(c); c = getchar()) if (c == ‘-‘) f = -f; for (; isdigit(c); c = getchar()) x = (x << 3) + (x << 1) + c - ‘0‘; x *= f; } int main() { read(n); for (int i = 1; i <= n; ++i) { read(sa[i]); rk[sa[i]] = i; } s[sa[1]] = ‘a‘; char now = ‘a‘; for (int i = 2; i <= n; ++i) { if (rk[sa[i - 1] + 1] < rk[sa[i] + 1]) s[sa[i]] = now; else { ++now; if (now > ‘z‘) { puts("-1"); return 0; } s[sa[i]] = now; } } for (int i = 1; i <= n; ++i) putchar(s[i]); puts(""); return 0; }
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CERC2008BZOJ4319Suffix reconstruction