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UVa 12712 && UVaLive 6653 Pattern Locker (排列组合)

题意:给定 一个n * n 的宫格,就是图案解锁,然后问你在区间 [l, r] 内的所有的个数进行组合,有多少种。

析:本来以为是数位DP,后来仔细一想是排列组合,因为怎么组合都行,不用考虑实际要考虑的比如 要连13,必须经过2,这个可以不用。

所以这题就是A(n,m)。剩下的就简单了。

代码如下:

#pragma comment(linker, "/STACK:1024000000,1024000000")#include <cstdio>#include <string>#include <cstdlib>#include <cmath>#include <iostream>#include <cstring>#include <set>#include <queue>#include <algorithm>#include <vector>#include <map>#include <cctype>#include <cmath>#include <stack>//#include <tr1/unordered_map>#define freopenr freopen("in.txt", "r", stdin)#define freopenw freopen("out.txt", "w", stdout)using namespace std;//using namespace std :: tr1;typedef long long LL;typedef pair<int, int> P;const int INF = 0x3f3f3f3f;const double inf = 0x3f3f3f3f3f3f;const LL LNF = 0x3f3f3f3f3f3f;const double PI = acos(-1.0);const double eps = 1e-8;const int maxn = 10000 + 5;const LL mod = 10000000000007;const int N = 1e6 + 5;const int dr[] = {-1, 0, 1, 0, 1, 1, -1, -1};const int dc[] = {0, 1, 0, -1, 1, -1, 1, -1};const char *Hex[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"};inline LL gcd(LL a, LL b){  return b == 0 ? a : gcd(b, a%b); }int n, m;const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};inline int Min(int a, int b){ return a < b ? a : b; }inline int Max(int a, int b){ return a > b ? a : b; }inline LL Min(LL a, LL b){ return a < b ? a : b; }inline LL Max(LL a, LL b){ return a > b ? a : b; }inline bool is_in(int r, int c){    return r >= 0 && r < n && c >= 0 && c < m;}LL sum[maxn];int main(){    int T;  cin >> T;    for(int kase = 1; kase <= T; ++kase){        int k;        scanf("%d %d %d", &n, &m, &k);        n = n * n;        LL ans = 0;        m = n - m + 1;  k = n - k + 1;        sum[n] = n;        for(int i = n-1; i >= 1; --i)  sum[i] = (sum[i+1] * i) % mod;        for(int i = k; i <= m; ++i)  ans = (ans + sum[i]) % mod;        printf("Case %d: %lld\n", kase, ans);    }    return 0;}

 

UVa 12712 && UVaLive 6653 Pattern Locker (排列组合)