1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
| class {
private:
inline int calcOverlap(const string& s1, const string& s2) {
int start = s1.length() - s2.length();
start = max(0, start);
for (int i = start; i < s1.length(); i++) {
int len = s1.length() - i;
if (s1.substr(i, len) == s2.substr(0, len))
return len;
}
return 0;
}
inline bool contains(int cnt, int i) {
return (cnt & (1 << i)) != 0;
}大专栏 Leetcode 943. Find the Shortest Superstring（DP）>
public:
string shortestSuperstring(vector<string>& A) {
int n = A.size();
if (n == 1) return A[0];
int overlap[n][n];
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++)
overlap[i][j] = calcOverlap(A[i], A[j]);
const int MAX_CNT = (1 << n);
int f[MAX_CNT][n], parent[MAX_CNT][n];
for (int i = 0; i < n; i++) {
f[1 << i][i] = 0;
parent[1 << i][i] = -1;
}
int ans = -1;
int p = -1;
for (int cnt = 2; cnt <= n; cnt++) {
for (int i = 0; i < MAX_CNT; i++) {
if (__builtin_popcount(i) != cnt) continue;
for (int j = 0; j < n; j++) {
if (!contains(i, j)) continue;
f[i][j] = -1;
int nmask = i ^ (1 << j);
for (int k = 0; k < n; k++) {
if (!contains(nmask, k)) continue;
if (f[nmask][k] + overlap[k][j] > f[i][j]) {
f[i][j] = f[nmask][k] + overlap[k][j];
parent[i][j] = k;
}
}
if (cnt == n && f[i][j] > ans) {
ans = f[i][j];
p = j;
}
}
}
}
string str;
int nmask = MAX_CNT - 1;
while (true) {
int par = parent[nmask][p];
if (par == -1) {
str = A[p] + str;
break;
}
str = A[p].substr(overlap[par][p], A[p].length() - overlap[par][p]) + str;
nmask ^= (1 << p);
p = par;
}
return str;
}
};
|
