等差素数组
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#include <stdio.h> #include <stdlib.h> int isprime(long long x) { if(x<=1) return 0; if(x==2) return 1; if(x%2==0) return 0; for(int i=3;i*i<=x;i+=2) { if(x%i==0) return 0; } return 1; } int check(long long a,long long d,int len) { for(int i=0;i<len;i++) { if(!isprime(a+i*d)) return 0; } return 1; } int main(int argc, char *argv[]) { int len=10; long long base_d=210; long long d=base_d; while(1) { for(long long a=2;;a++) { if(isprime(a)) { if(check(a,d,len)) { printf("%lld",d); return 0; } } if(a>1000000) break; } d+=base_d; } return 0; }
承压计算
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#include <stdio.h> #include <stdlib.h> int main(int argc, char *argv[]) { double a[31][31]={{0},{ 0,7},{ 0,5,8},{ 0,7,8,8},{ 0,9,2,7,2},{ 0,8,1,4,9,1},{ 0,8,1,8,8,4,1},{ 0,7,9,6,1,4,5,4},{ 0,5,6,5,5,6,9,5,6},{ 0,5,5,4,7,9,3,5,5,1},{ 0,7,5,7,9,7,4,7,3,3,1},{ 0,4,6,4,5,5,8,8,3,2,4,3},{ 0,1,1,3,3,1,6,6,5,5,4,4,2},{ 0,9,9,9,2,1,9,1,9,2,9,5,7,9},{ 0,4,3,3,7,7,9,3,6,1,3,8,8,3,7},{ 0,3,6,8,1,5,3,9,5,8,3,8,1,8,3,3},{ 0,8,3,2,3,3,5,5,8,5,4,2,8,6,7,6,9},{ 0,8,1,8,1,8,4,6,2,2,1,7,9,4,2,3,3,4},{ 0,2,8,4,2,2,9,9,2,8,3,4,9,6,3,9,4,6,9},{ 0,7,9,7,4,9,7,6,6,2,8,9,4,1,8,1,7,2,1,6},{ 0,9,2,8,6,4,2,7,9,5,4,1,2,5,1,7,3,9,8,3,3},{ 0,5,2,1,6,7,9,3,2,8,9,5,5,6,6,6,2,1,8,7,9,9},{ 0,6,7,1,8,8,7,5,3,6,5,4,7,3,4,6,7,8,1,3,2,7,4},{ 0,2,2,6,3,5,3,4,9,2,4,5,7,6,6,3,2,7,2,4,8,5,5,4},{ 0,7,4,4,5,8,3,3,8,1,8,6,3,2,1,6,2,6,4,6,3,8,2,9,6},{ 0,1,2,4,1,3,3,5,3,4,9,6,3,8,6,5,9,1,5,3,2,6,8,8,5,3},{ 0,2,2,7,9,3,3,2,8,6,9,8,4,4,9,5,8,2,6,3,4,8,4,9,3,8,8},{ 0,7,7,7,9,7,5,2,7,9,2,5,1,9,2,6,5,3,9,3,5,7,3,5,4,2,8,9},{ 0,7,7,6,6,8,7,5,5,8,2,4,7,7,4,7,2,6,9,2,1,8,2,9,8,5,7,3,6},{ 0,5,9,4,5,5,7,5,5,6,3,5,3,9,5,8,9,5,4,1,2,6,1,4,3,5,3,2,4,1}}; for(int i=0;i<=29;i++) { for(int j=0;j<=29;j++) { a[i+1][j]+=a[i][j]*1.0/2; a[i+1][j+1]+=a[i][j]*1.0/2; } } double max=0.0,min=999999999; for(int i=1;i<=30;i++) { if(a[30][i]>max) max=a[30][i]; if(a[30][i]<max) min=a[30][i]; } long long ans=(long long)2086458231/min*max; printf("%lld",ans); return 0; }
方格分割（DFS）
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#include <stdio.h> #include <stdlib.h> int visit[7][7]={0}; int dx[]={1,-1,0,0}; int dy[]={0,0,1,-1}; int cnt=0; void dfs(int x,int y) { if(x==0||y==0||x==6||y==6) { cnt++; return ; } for(int i=0;i<=3;i++) { if(!visit[x+dx[i]][y+dy[i]]) { visit[x+dx[i]][y+dy[i]]=1; visit[6-x-dx[i]][6-y-dy[i]]=1; dfs(x+dx[i],y+dy[i]); visit[x+dx[i]][y+dy[i]]=0; visit[6-x-dx[i]][6-y-dy[i]]=0; } } } int main(int argc, char *argv[]) { visit[3][3]=1; dfs(3,3); printf("%d",cnt/4); return 0; }
日期问题
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#include <stdio.h> int a,b,c; int check(int year,int month,int day) { year=year%100; if(a==year&&b==month&&c==day) return 1; if(a==month&&b==day&&c==year) return 1; if(a==day&&b==month&&c==year) return 1; return 0; } int main() { int month_day[]={0,31,28,31,30,31,30,31,31,30,31,30,31}; int yy,mm,dd; scanf("%d/%d/%d",&a,&b,&c); for(yy=1960;yy<=2059;yy++) { if(yy%400==0||(yy%4==0&&yy%100!=0)) month_day[2]=29; else month_day[2]=28; for(mm=1;mm<=12;mm++) { for(dd=1;dd<=month_day[mm];dd++) { if(check(yy,mm,dd)) printf("%d-%02d-%02d\n",yy,mm,dd); } } } return 0; }
包子凑数（动态规划）
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#include <stdio.h> #include <stdlib.h> int gcd(int a,int b) { while(b) { int t=b; b=a%b; a=t; } return a; } int main(int argc, char *argv[]) { int n; scanf("%d",&n); int a[n]; for(int i=0;i<n;i++) { scanf("%d",&a[i]); } int gcd_all=a[0]; for(int i=1;i<n;i++) { gcd_all=gcd(gcd_all,a[i]); } if(gcd_all!=1) { printf("INF"); return 0; } int dp[10000]; int max=10000; for(int i=0;i<=max;i++) { dp[i]=0; } dp[0]=1; for(int i=0;i<n;i++) { for(int j=a[i];j<=max;j++) { if(dp[j-a[i]]) dp[j]=1; } } int cnt=0; for(int i=0;i<=max;i++) { if(!dp[i]) cnt++; } printf("%d",cnt); return 0; }
全球变暖（DFS）
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#include <stdio.h> #include <string.h> #define MAX 1010 char g[MAX][MAX]; int n,ans,visit[MAX][MAX]; int dx[]={0,0,1,-1}; int dy[]={1,-1,0,0}; int flag=1; void dfs(int sx,int sy) { visit[sx][sy]=1; int has_water=0; for(int i=0;i<4;i++) { int x=sx+dx[i],y=sy+dy[i]; if(x<0||y<0||x>=n||y>=n) continue; if(g[x][y]=='.') { has_water=1; continue; } if(!visit[x][y]&&g[x][y]=='#') dfs(x,y); } if(!has_water) flag=0; } int main(int argc, char *argv[]) { scanf("%d",&n); for(int i=0;i<n;i++) { scanf("%s",g[i]); } memset(visit,0,sizeof(visit)); ans=0; for(int i=0;i<n;i++) { for(int j=0;j<n;j++) { if(g[i][j]=='#'&&!visit[i][j]) { flag=1; dfs(i,j); if(flag) ans++; } } } printf("%d",ans); return 0; }
