【BZOJ】1653: [Usaco2006 Feb]Backward Digit Sums(暴力)
2014-09-07 08:07
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http://www.lydsy.com/JudgeOnline/problem.php?id=1653
看了题解才会的。。T_T
我们直接枚举每一种情况(这里用next_permutation,全排列)
然后判断是否符合情况(累加判断)
OUTPUT DETAILS:
There are other possible sequences, such as 3 2 1 4, but 3 1 2 4
is the lexicographically smallest.
看了题解才会的。。T_T
我们直接枚举每一种情况(这里用next_permutation,全排列)
然后判断是否符合情况(累加判断)
#include <cstdio> #include <cstring> #include <cmath> #include <string> #include <iostream> #include <algorithm> #include <queue> using namespace std; #define rep(i, n) for(int i=0; i<(n); ++i) #define for1(i,a,n) for(int i=(a);i<=(n);++i) #define for2(i,a,n) for(int i=(a);i<(n);++i) #define for3(i,a,n) for(int i=(a);i>=(n);--i) #define for4(i,a,n) for(int i=(a);i>(n);--i) #define CC(i,a) memset(i,a,sizeof(i)) #define read(a) a=getint() #define print(a) printf("%d", a) #define dbg(x) cout << #x << " = " << x << endl #define printarr(a, n, m) rep(aaa, n) { rep(bbb, m) cout << a[aaa][bbb]; cout << endl; } inline const int getint() { int r=0, k=1; char c=getchar(); for(; c<'0'||c>'9'; c=getchar()) if(c=='-') k=-1; for(; c>='0'&&c<='9'; c=getchar()) r=r*10+c-'0'; return k*r; } inline const int max(const int &a, const int &b) { return a>b?a:b; } inline const int min(const int &a, const int &b) { return a<b?a:b; } int n, m; int a[15], f[15]; int main() { read(n); read(m); for1(i, 1, n) a[i]=i; do { memcpy(f, a, sizeof(a)); for1(i, 1, n-1) for3(j, i, 1) f[j]+=f[j+1]; if(f[1]==m) { printf("%d", a[1]); for1(i, 2, n) printf(" %d", a[i]); puts(""); break; } }while(next_permutation(a+1, a+1+n)); return 0; }
Description
FJ and his cows enjoy playing a mental game. They write down the numbers from 1 to N (1 <= N <= 10) in a certain order and then sum adjacent numbers to produce a new list with one fewer number. They repeat this until only a single number is left. For example, one instance of the game (when N=4) might go like this: 3 1 2 4 4 3 6 7 9 16 Behind FJ's back, the cows have started playing a more difficult game, in which they try to determine the starting sequence from only the final total and the number N. Unfortunately, the game is a bit above FJ's mental arithmetic capabilities. Write a program to help FJ play the game and keep up with the cows.Input
* Line 1: Two space-separated integers: N and the final sum.Output
* Line 1: An ordering of the integers 1..N that leads to the given sum. If there are multiple solutions, choose the one that is lexicographically least, i.e., that puts smaller numbers first.Sample Input
4 16Sample Output
3 1 2 4OUTPUT DETAILS:
There are other possible sequences, such as 3 2 1 4, but 3 1 2 4
is the lexicographically smallest.
HINT
Source
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