AtCoder Beginner Contest 161 比賽人數9927 快,比賽開始後5分鐘看到所有題
AtCoder Beginner Contest 161 D Lunlun Number 打表+找規律+構造
總目錄詳見https://blog.csdn.net/mrcrack/article/details/104454762
在線測評地址https://atcoder.jp/contests/abc161/tasks/abc161_d
此類問題，手工模擬，對應的是成千上萬的數據，還是打表，不容易模擬數據出錯。
打表代碼如下
#include <cstdio>
#include <algorithm>
#define LL long long
using namespace std;
int a[15];
int judge(LL x){
int i,top=0;
while(x){
a[++top]=x%10;
x/=10;
}
for(i=2;i<=top;i++)
if(abs(a[i]-a[i-1])>1)return 0;
return 1;
}
int main(){
int cnt=0;
LL i,n;
scanf("%lld",&n);
for(i=1;i<=n;i++)
if(judge(i))cnt++,printf("%lld,",i);
printf("\ncnt=%d\n",cnt);
return 0;
}
將打表代碼編譯，運行，輸入9999,得到如下輸出數據
1,2,3,4,5,6,7,8,9,
10,11,12,
21,22,23,
32,33,34,
43,44,45,
54,55,56,
65,66,67,
76,77,78,
87,88,89,
98,99,
100,101,
110,111,112,
121,122,123,
210,211,212,
221,222,223,
232,233,234,
321,322,323,
332,333,334,
343,344,345,
432,433,434,
443,444,445,
454,455,456,
543,544,545,
554,555,556,
565,566,567,
654,655,656,
665,666,667,
676,677,678,
765,766,767,
776,777,778,
787,788,789,
876,877,878,
887,888,889,
898,899,
987,988,989,
998,999,
1000,1001,
1010,1011,1012,
1100,1101,
1110,1111,1112,
1121,1122,1123,
1210,1211,1212,
1221,1222,1223,
1232,1233,1234,
2100,2101,
2110,2111,2112,
2121,2122,2123,
2210,2211,2212,
2221,2222,2223,
2232,2233,2234,
2321,2322,2323,
2332,2333,2334,
2343,2344,2345,
3210,3211,3212,
3221,3222,3223,
3232,3233,3234,
3321,3322,3323,
3332,3333,3334,
3343,3344,3345,
3432,3433,3434,
3443,3444,3445,
3454,3455,3456,
4321,4322,4323,
4332,4333,4334,
4343,4344,4345,
4432,4433,4434,
4443,4444,4445,
4454,4455,4456,
4543,4544,4545,
4554,4555,4556,
4565,4566,4567,
5432,5433,5434,
5443,5444,5445,
5454,5455,5456,
5543,5544,5545,
5554,5555,5556,
5565,5566,5567,
5654,5655,5656,
5665,5666,5667,
5676,5677,5678,
6543,6544,6545,
6554,6555,6556,
6565,6566,6567,
6654,6655,6656,
6665,6666,6667,
6676,6677,6678,
6765,6766,6767,
6776,6777,6778,
6787,6788,6789,
7654,7655,7656,
7665,7666,7667,
7676,7677,7678,
7765,7766,7767,
7776,7777,7778,
7787,7788,7789,
7876,7877,7878,
7887,7888,7889,
7898,7899,
8765,8766,8767,
8776,8777,8778,
8787,8788,8789,
8876,8877,8878,
8887,8888,8889,
8898,8899,
8987,8988,8989,
8998,8999,
9876,9877,9878,
9887,9888,9889,
9898,9899,
9987,9988,9989,
9998,9999,
cnt=327
挑出特殊數據進行研究
98,99,
100,101,
898,899,
998,999,
1000,1001,
1100,1101,
2100,2101,
7898,7899,
8898,8899,
8998,8999,
9898,9899,
9998,9999,
以8,9,10爲例展示數據生成過程
8生成的2位數有87,88,89
9生成的2位數有98,99
10生成的2位數有100,101
其它數據生成過程，不外乎上述三種過程。
熟知數據生成過程後，構造出符合題意的100000組數據，待測試數據挑選。
AC代碼如下
#include <stdio.h>
#define maxn 100010
#define LL long long
LL rd[maxn]={1,2,3,4,5,6,7,8,9};
int main(){
int i,id,k;
scanf("%d",&k);
i=9,id=0;
while(i<k){
if(rd[id]%10==0){//10生成的2位數有100,101
rd[i]=rd[id]*10;
rd[i+1]=rd[id]*10+1;
i+=2;
}else if(rd[id]%10==9){//9生成的2位數有98,99
rd[i]=rd[id]*10+8;
rd[i+1]=rd[id]*10+9;
i+=2;
}else{//8生成的2位數有87,88,89
rd[i]=rd[id]*10+rd[id]%10-1;
rd[i+1]=rd[id]*10+rd[id]%10;
rd[i+2]=rd[id]*10+rd[id]%10+1;
i+=3;
}
id++;
}
printf("%lld\n",rd[k-1]);
return 0;
}