作业：

#include <iostream>
using namespace std;
int main(){int a[110][110]={0},b[110][110]={0},n;cin>>n;for(int i=1;i<=n;i++){for(int j=1;j<=i;j++){cin>>a[i][j];}}for(int i=n-1;i>=1;i--){for(int j=1;j<=i;j++){a[i][j]=a[i][j]+max(a[i+1][j],a[i+1][j+1]);}}cout<<a[1][1];return 0;
}

#include <iostream>
using namespace std;
int main(){int a[110][110]={0},b[110][110]={0},m,n;cin>>m>>n;for(int i=1;i<=m;i++){for(int j=1;j<=n;j++){cin>>a[i][j];}}for(int i=1;i<=m;i++){for(int j=1;j<=n;j++){a[i][j]=a[i][j]+max(a[i-1][j],a[i][j-1]);}}cout<<a[m][n];return 0;
}

#include <iostream>
using namespace std;
int main(){int a[30][30]={0},m,n,x,y;cin>>x>>y>>m>>n;int dx[9][2]={{m,n},{m+1,n+2},{m+1,n-2},{m-1,n+2},{m-1,n-2},{m-2,n+1},{m-2,n-1},{m+2,n+1},{m-+2,n-1}};int t=1;for(int i=0;i<=8;i++)a[dx[i][0]][dx[i][1]]=-1;for(int i=0;i<=y;i++){if(a[0][i]==-1)t=-1;else a[0][i]=t;}t=1;for(int i=0;i<=x;i++){if(a[i][0]==-1)t=-1;else a[i][0]=t;}for(int i=1;i<=x;i++){for(int j=1;j<=y;j++){if(a[i][j]!=-1)a[i][j]=(a[i-1][j]==-1?0:a[i-1][j])+(a[i][j-1]==-1?0:a[i][j-1]);}}cout<<a[x][y];return 0;
}

#include <iostream>
using namespace std;
int main(){int a[110][110]={0},b[110][110]={0},n;cin>>n;for(int i=1;i<=n;i++){for(int j=1;j<=i;j++){cin>>a[i][j];}}for(int i=n-1;i>=1;i--){for(int j=1;j<=i;j++){a[i][j]=a[i][j]+max(a[i+1][j],a[i+1][j+1]);b[i+1][j]=(a[i+1][j]>a[i+1][j+1]?j:j+1);}}b[1][1]=1;for(int i=n;i>1;i--){cout<<i<<','<<b[i][1]<<"->";}cout<<1<<','<<b[1][1]<<endl;cout<<a[1][1];return 0;
}

#include <iostream>
using namespace std;
int main(){int a[110][110]={0},b[110][110]={0},c[110][110]={0},m,n;int ns[100][2]={0},l=0;int dx[2][2]={{-1,0},{0,-1}};cin>>m>>n;for(int i=1;i<=m;i++){for(int j=1;j<=n;j++){cin>>a[i][j];c[i][j]=a[i][j];}}for(int i=1;i<=m;i++){for(int j=1;j<=n;j++){c[i][j]=c[i][j]+max(c[i-1][j],c[i][j-1]);b[i][j]=(c[i-1][j]>c[i][j-1]?0:1);//0up 1left}}int x=m,y=n;while(x>=1&&y>=1){ns[l][0]=x;ns[l][1]=y;l++;x+=dx[b[x][y]][0];y+=dx[b[x][y]][1];}cout<<a[1][1];for(int i=l-1;i>=0;i--){cout<<'-'<<a[ns[i][0]][ns[i][1]];}return 0;
}

#include <iostream>
using namespace std;
int main(){char a[2][110][110];int n;cin>>n;for(int i=1;i<=n;i++){for(int j=1;j<=n;j++){cin>>a[1][i][j];}}int m;cin>>m;for(int i=1;i<=m;i++){bool t=i%2;//原bool tf=!t;//新for(int x=1;x<=n;x++){for(int y=1;y<=n;y++){a[tf][x][y]=a[t][x][y];}}for(int x=1;x<=n;x++){for(int y=1;y<=n;y++){if(a[t][x][y]=='@'){a[tf][x][y]='@';a[tf][x+1][y]=(a[t][x+1][y]=='.'?'!':a[t][x+1][y]);a[tf][x-1][y]=(a[t][x-1][y]=='.'?'!':a[t][x-1][y]);a[tf][x][y+1]=(a[t][x][y+1]=='.'?'!':a[t][x][y+1]);a[tf][x][y-1]=(a[t][x][y-1]=='.'?'!':a[t][x][y-1]);}}}for(int x=1;x<=n;x++){for(int y=1;y<=n;y++){if(a[tf][x][y]=='!'){a[tf][x][y]='@';}}}}int cnt=0;for(int x=1;x<=n;x++){for(int y=1;y<=n;y++){if(a[m%2][x][y]=='@')cnt++;}}cout<<cnt;return 0;
}