题目链接：http://www.nowcoder.com/test/1725829/summary
1、构造回文
解法：倒过来存一遍，对这两个字符串做一次lcs。这样lcs就是回文的，把不包含于lcs的字符删掉就行了。记录字符个数那就直接用串总长度减去lcs长度即可。
1 /* 2 ┓┏┓┏┓┃キリキリ♂ mind！ 3 ┛┗┛┗┛┃＼○／ 4 ┓┏┓┏┓┃ / 5 ┛┗┛┗┛┃ノ) 6 ┓┏┓┏┓┃ 7 ┛┗┛┗┛┃ 8 ┓┏┓┏┓┃ 9 ┛┗┛┗┛┃ 10 ┓┏┓┏┓┃ 11 ┛┗┛┗┛┃ 12 ┓┏┓┏┓┃ 13 ┃┃┃┃┃┃ 14 ┻┻┻┻┻┻ 15 */ 16 #include <algorithm> 17 #include <iostream> 18 #include <iomanip> 19 #include <cstring> 20 #include <climits> 21 #include <complex> 22 #include <fstream> 23 #include <cassert> 24 #include <cstdio> 25 #include <bitset> 26 #include <vector> 27 #include <deque> 28 #include <queue> 29 #include <stack> 30 #include <ctime> 31 #include <set> 32 #include <map> 33 #include <cmath> 34 using namespace std; 35 #define fr first 36 #define sc second 37 #define cl clear 38 #define BUG puts("here!!!") 39 #define W(a) while(a--) 40 #define pb(a) push_back(a) 41 #define Rlf(a) scanf("%lf", &a); 42 #define Rint(a) scanf("%d", &a) 43 #define Rll(a) scanf("%I64d", &a) 44 #define Rs(a) scanf("%s", a) 45 #define Cin(a) cin >> a 46 #define FRead() freopen("in", "r", stdin) 47 #define FWrite() freopen("out", "w", stdout) 48 #define Rep(i, len) for(int i = 0; i < (len); i++) 49 #define For(i, a, len) for(int i = (a); i < (len); i++) 50 #define Cls(a) memset((a), 0, sizeof(a)) 51 #define Clr(a, x) memset((a), (x), sizeof(a)) 52 #define Full(a) memset((a), 0x7f7f, sizeof(a)) 53 #define lrt rt << 1 54 #define rrt rt << 1 | 1 55 #define pi 3.14159265359 56 #define RT return 57 #define lowbit(x) x & (-x) 58 #define onenum(x) __builtin_popcount(x) 59 typedef long long LL; 60 typedef long double LD; 61 typedef unsigned long long ULL; 62 typedef pair<int, int> pii; 63 typedef pair<string, int> psi; 64 typedef map<string, int> msi; 65 typedef vector<int> vi; 66 typedef vector<LL> vl; 67 typedef vector<vl> vvl; 68 typedef vector<bool> vb; 69 70 const int maxn = 1010; 71 char s[maxn]; 72 char e[maxn]; 73 int dp[maxn][maxn]; 74 75 int main() { 76 // FRead(); 77 while(~Rs(s+1)) { 78 Cls(dp); 79 int n = strlen(s+1); 80 For(i, 1, n+1) e[i] = s[n-i+1]; 81 For(i, 1, n+1) { 82 dp[i][0] = 0; 83 For(j, 1, n+1) { 84 if(s[i] == e[j]) { 85 dp[i][j] = max(dp[i][j], dp[i-1][j-1]+1); 86 } 87 dp[i][j] = max(dp[i][j], max(dp[i-1][j], dp[i][j-1])); 88 } 89 } 90 printf("%d ", n-dp[n][n]); 91 } 92 RT 0; 93 }
2、算法基础-字符移位
解法：模拟，n<=1010所以O(n²)可破。从后往前扫，尽量找靠后的大写字符，然后一路交换到最后，注意别和已经确定位置的字符冲突就行。
1 /* 2 ┓┏┓┏┓┃キリキリ♂ mind！ 3 ┛┗┛┗┛┃＼○／ 4 ┓┏┓┏┓┃ / 5 ┛┗┛┗┛┃ノ) 6 ┓┏┓┏┓┃ 7 ┛┗┛┗┛┃ 8 ┓┏┓┏┓┃ 9 ┛┗┛┗┛┃ 10 ┓┏┓┏┓┃ 11 ┛┗┛┗┛┃ 12 ┓┏┓┏┓┃ 13 ┃┃┃┃┃┃ 14 ┻┻┻┻┻┻ 15 */ 16 #include <algorithm> 17 #include <iostream> 18 #include <iomanip> 19 #include <cstring> 20 #include <climits> 21 #include <complex> 22 #include <fstream> 23 #include <cassert> 24 #include <cstdio> 25 #include <bitset> 26 #include <vector> 27 #include <deque> 28 #include <queue> 29 #include <stack> 30 #include <ctime> 31 #include <set> 32 #include <map> 33 #include <cmath> 34 using namespace std; 35 #define fr first 36 #define sc second 37 #define cl clear 38 #define BUG puts("here!!!") 39 #define W(a) while(a--) 40 #define pb(a) push_back(a) 41 #define Rlf(a) scanf("%lf", &a); 42 #define Rint(a) scanf("%d", &a) 43 #define Rll(a) scanf("%I64d", &a) 44 #define Rs(a) scanf("%s", a) 45 #define Cin(a) cin >> a 46 #define FRead() freopen("in", "r", stdin) 47 #define FWrite() freopen("out", "w", stdout) 48 #define Rep(i, len) for(int i = 0; i < (len); i++) 49 #define For(i, a, len) for(int i = (a); i < (len); i++) 50 #define Cls(a) memset((a), 0, sizeof(a)) 51 #define Clr(a, x) memset((a), (x), sizeof(a)) 52 #define Full(a) memset((a), 0x7f7f, sizeof(a)) 53 #define lrt rt << 1 54 #define rrt rt << 1 | 1 55 #define pi 3.14159265359 56 #define RT return 57 #define lowbit(x) x & (-x) 58 #define onenum(x) __builtin_popcount(x) 59 typedef long long LL; 60 typedef long double LD; 61 typedef unsigned long long ULL; 62 typedef pair<int, int> pii; 63 typedef pair<string, int> psi; 64 typedef map<string, int> msi; 65 typedef vector<int> vi; 66 typedef vector<LL> vl; 67 typedef vector<vl> vvl; 68 typedef vector<bool> vb; 69 70 const int maxn = 1010; 71 char s[maxn]; 72 int main() { 73 // FRead(); 74 while(~Rs(s)) { 75 int n = strlen(s); 76 int cnt = 0; 77 for(int i = n - 1; i >= 0; i--) { 78 if(s[i] >= 'A' && s[i] <= 'Z') { 79 For(j, i, n-cnt-1) swap(s[j], s[j+1]); 80 cnt++; 81 } 82 } 83 printf("%s ", s); 84 } 85 RT 0; 86 }
3、有趣的数字
解法：先排序，最大的差的个数好找，就是最头上的相同数字的个数和最末尾的相同数字的个数的乘积。最小的差考虑了一下，因为n<=100000所以只能是O(n)或者O(nlgn)的做，显然线性的是不行的。既然排好序了，我们就有一条性质，那就是存在序列中三个连续的数字a,b,c，有c-b < c-a。所以我们先找到最小的差，这个值一定是序列中相邻两个数字的差。然后枚举每一个数字和它之前的数字，如果差值和最小的差不相等，那后面的数字就没有必要再遍历了。这个复杂度大概是O(n*k)。
1 /* 2 ┓┏┓┏┓┃キリキリ♂ mind！ 3 ┛┗┛┗┛┃＼○／ 4 ┓┏┓┏┓┃ / 5 ┛┗┛┗┛┃ノ) 6 ┓┏┓┏┓┃ 7 ┛┗┛┗┛┃ 8 ┓┏┓┏┓┃ 9 ┛┗┛┗┛┃ 10 ┓┏┓┏┓┃ 11 ┛┗┛┗┛┃ 12 ┓┏┓┏┓┃ 13 ┃┃┃┃┃┃ 14 ┻┻┻┻┻┻ 15 */ 16 #include <algorithm> 17 #include <iostream> 18 #include <iomanip> 19 #include <cstring> 20 #include <climits> 21 #include <complex> 22 #include <fstream> 23 #include <cassert> 24 #include <cstdio> 25 #include <bitset> 26 #include <vector> 27 #include <deque> 28 #include <queue> 29 #include <stack> 30 #include <ctime> 31 #include <set> 32 #include <map> 33 #include <cmath> 34 using namespace std; 35 #define fr first 36 #define sc second 37 #define cl clear 38 #define BUG puts("here!!!") 39 #define W(a) while(a--) 40 #define pb(a) push_back(a) 41 #define Rlf(a) scanf("%lf", &a); 42 #define Rint(a) scanf("%d", &a) 43 #define Rll(a) scanf("%I64d", &a) 44 #define Rs(a) scanf("%s", a) 45 #define Cin(a) cin >> a 46 #define FRead() freopen("in", "r", stdin) 47 #define FWrite() freopen("out", "w", stdout) 48 #define Rep(i, len) for(int i = 0; i < (len); i++) 49 #define For(i, a, len) for(int i = (a); i < (len); i++) 50 #define Cls(a) memset((a), 0, sizeof(a)) 51 #define Clr(a, x) memset((a), (x), sizeof(a)) 52 #define Full(a) memset((a), 0x7f7f, sizeof(a)) 53 #define lrt rt << 1 54 #define rrt rt << 1 | 1 55 #define pi 3.14159265359 56 #define RT return 57 #define lowbit(x) x & (-x) 58 #define onenum(x) __builtin_popcount(x) 59 typedef long long LL; 60 typedef long double LD; 61 typedef unsigned long long ULL; 62 typedef pair<int, int> pii; 63 typedef pair<string, int> psi; 64 typedef map<string, int> msi; 65 typedef vector<int> vi; 66 typedef vector<LL> vl; 67 typedef vector<vl> vvl; 68 typedef vector<bool> vb; 69 70 const int maxn = 100100; 71 int n; 72 int a[maxn]; 73 int sub; 74 int ret1, ret2; 75 76 int main() { 77 // FRead(); 78 while(~Rint(n)) { 79 For(i, 1, n+1) Rint(a[i]); 80 sort(a+1, a+n+1); sub = 0x7f7f7f; ret1 = 0; 81 int l = 0, r = 0; 82 For(i, 1, n) sub = min(a[i+1]-a[i], sub); 83 For(i, 1, n+1) { 84 for(int j = i - 1; j >= 1; j--) { 85 if(a[i] - a[j] == sub) ret1++; 86 else break; 87 } 88 } 89 For(i, 1, n+1) { 90 if(a[1] == a[i]) l++; 91 else break; 92 } 93 for(int i = n; i >= 1; i--) { 94 if(a[n] == a[i]) r++; 95 else break; 96 } 97 ret2 = l * r; 98 printf("%d %d ", ret1, ret2); 99 } 100 RT 0; 101 }