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※ 引述《ACGfans (ACGfans)》之銘言: : 從 1 數到 n (n > 1) : 1 這個數字出現的次數剛好為 n : Q1 : n 最小為何? : Q2 : n 最大為何? 這題想了半天感覺只能用程式跑 最小為 199981 最大為 1111111110 但可能無上限, 以下為程式碼 int main() { unsigned int i, j, num = 0; for(i=1;i<4294967295;i++) { for(j=i;j!=0;j/=10) { if (j%10 == 1) num++; } if(i==num) printf("the same! i=%d \n", i); } printf("end1\n"); return 0; } Result: the same! i=1 the same! i=199981 the same! i=199982 the same! i=199983 the same! i=199984 the same! i=199985 the same! i=199986 the same! i=199987 the same! i=199988 the same! i=199989 the same! i=199990 the same! i=200000 the same! i=200001 the same! i=1599981 the same! i=1599982 the same! i=1599983 the same! i=1599984 the same! i=1599985 the same! i=1599986 the same! i=1599987 the same! i=1599988 the same! i=1599989 the same! i=1599990 the same! i=2600000 the same! i=2600001 the same! i=13199998 the same! i=35000000 the same! i=35000001 the same! i=35199981 the same! i=35199982 the same! i=35199983 the same! i=35199984 the same! i=35199985 the same! i=35199986 the same! i=35199987 the same! i=35199988 the same! i=35199989 the same! i=35199990 the same! i=35200000 the same! i=35200001 the same! i=117463825 the same! i=500000000 the same! i=500000001 the same! i=500199981 the same! i=500199982 the same! i=500199983 the same! i=500199984 the same! i=500199985 the same! i=500199986 the same! i=500199987 the same! i=500199988 the same! i=500199989 the same! i=500199990 the same! i=500200000 the same! i=500200001 the same! i=501599981 the same! i=501599982 the same! i=501599983 the same! i=501599984 the same! i=501599985 the same! i=501599986 the same! i=501599987 the same! i=501599988 the same! i=501599989 the same! i=501599990 the same! i=502600000 the same! i=502600001 the same! i=513199998 the same! i=535000000 the same! i=535000001 the same! i=535199981 the same! i=535199982 the same! i=535199983 the same! i=535199984 the same! i=535199985 the same! i=535199986 the same! i=535199987 the same! i=535199988 the same! i=535199989 the same! i=535199990 the same! i=535200000 the same! i=535200001 the same! i=1111111110 -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 1.163.20.99 (臺灣) ※ 文章網址: https://www.ptt.cc/bbs/puzzle/M.1577870023.A.9B4.html
LPH66: 都跑出來了就來給個 https://oeis.org/A014778 01/01 20:04
cutekid: 推推(Y) 01/01 21:34
ACGfans: 正解 上限就是這樣了 n越大會差距越多 01/02 16:14