POJ 1743 Musical Theme 后缀数组 不可重叠最长重复子串

二分长度k 长度大于等于k的分成一组 每组sa最大的和最小的距离大于k 说明可行

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int maxn = 20010;int s[maxn];int sa[maxn];int t[maxn], t2[maxn], c[maxn];int rank[maxn], height[maxn];void build_sa(int m, int n){int i, *x = t, *y = t2;for(i = 0; i < m; i++)c[i] = 0;for(i = 0; i < n; i++)c[x[i] = s[i]]++;for(i = 1; i < m; i++)c[i] += c[i-1];for(i = n-1; i >= 0; i--)sa[--c[x[i]]] = i;for(int k = 1; k <= n; k <<= 1){int p = 0;for(i = n-k; i < n; i++)y[p++] = i;for(i = 0; i < n; i++)if(sa[i] >= k)y[p++] = sa[i] - k;for(i = 0; i < m; i++)c[i] = 0;for(i = 0; i < n; i++)c[x[y[i]]]++;for(i = 0; i < m; i++)c[i]+= c[i-1];for(i = n-1; i >= 0; i--)sa[--c[x[y[i]]]] = y[i];swap(x, y);p = 1; x[sa[0]] = 0;for(i = 1; i < n; i++)x[sa[i]] = y[sa[i-1]] == y[sa[i]] && y[sa[i-1]+k] == y[sa[i]+k] ? p-1 : p++;if(p >= n)break;m = p;}}void getHeight(int n){int k = 0;for(int i = 0; i <= n; i++)rank[sa[i]] = i;for(int i = 0; i < n; i++){if(k)k--;int j = sa[rank[i]-1];while(s[i+k] == s[j+k])k++;height[rank[i]] = k;}}bool ok(int n, int k){int ans1 = sa[1], ans2 = sa[1];for(int i = 2; i <= n; i++){if(height[i] < k){ans1 = ans2 = sa[i];}else{ans1 = max(ans1, sa[i]);ans2 = min(ans2, sa[i]);if(ans1-ans2 > k)return true;}}return false;}int main(){int n;while(scanf("%d", &n) && n){for(int i = 0; i < n; i++)scanf("%d", &s[i]);n--;for(int i = 0; i < n; i++)s[i] = s[i+1] - s[i] + 90;s[n] = 0;build_sa(200, n+1);getHeight(n);int l = 4, r = n+1;int ans = -1;while(l <= r){int m = (l+r) >> 1;if(ok(n, m)){l = m+1;ans = m;}elser = m-1;}printf("%d\n", ans+1);}return 0;}