虽然之前学过一点点，但是还是不会------现在好好跟着白书1.4节学一下——————
（1）数字三角形
d(i,j) = max(d(i+1,j),d(i+1,j+1)) + a[i][j]
hdu 2084
1 #include<iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include <cmath> 5 #include<stack> 6 #include<vector> 7 #include<map> 8 #include<set> 9 #include<queue> 10 #include<algorithm> 11 using namespace std; 12 13 typedef long long LL; 14 const int INF = (1<<30)-1; 15 const int mod=1000000007; 16 const int maxn=1000005; 17 18 int d[1005][1005],a[1005][1005]; 19 20 int main(){ 21 int T; 22 scanf("%d",&T); 23 while(T--){ 24 int n; 25 scanf("%d",&n); 26 memset(d,0,sizeof(d)); 27 for(int i = 1;i<=n;i++) 28 for(int j = 1;j<=i;j++) scanf("%d",&a[i][j]); 29 30 for(int i = n;i>=1;i--){ 31 for(int j = 1;j<=i;j++) 32 d[i][j] = max(d[i+1][j],d[i+1][j+1]) + a[i][j]; 33 } 34 printf("%d ",d[1][1]); 35 } 36 return 0; 37 }
（2）嵌套矩形
把图先建出来，然后d(i) = max(d(j) + 1)
nyoj 16
1 #include<iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include <cmath> 5 #include<stack> 6 #include<vector> 7 #include<map> 8 #include<set> 9 #include<queue> 10 #include<algorithm> 11 using namespace std; 12 13 typedef long long LL; 14 const int INF = (1<<30)-1; 15 const int mod=1000000007; 16 const int maxn=1000005; 17 18 int g[1005][1005]; 19 int d[1005]; 20 int n; 21 22 struct node{ 23 int x,y; 24 }a[maxn]; 25 26 int dp(int i){ 27 int& ans = d[i]; 28 if(ans > 0) return ans; 29 ans = 1; 30 for(int j = 1;j <= n;j++) 31 if(g[i][j]) ans = max(ans,dp(j) + 1); 32 33 return ans; 34 } 35 36 int work(){ 37 int res = -1; 38 for(int i = 1;i <= n;i++) res = max(res,dp(i)); 39 return res; 40 } 41 42 int main(){ 43 int T; 44 scanf("%d",&T); 45 while(T--){ 46 scanf("%d",&n); 47 for(int i = 1;i <= n;i++) scanf("%d %d",&a[i].x,&a[i].y); 48 memset(g,0,sizeof(g)); 49 memset(d,0,sizeof(d)); 50 51 for(int i = 1;i <= n;i++){ 52 for(int j = 1;j <= n;j++){ 53 if((a[i].x > a[j].x && a[i].y > a[j].y) || (a[i].x > a[j].y && a[i].y > a[j].x )) 54 g[i][j] = 1; 55 } 56 } 57 58 printf("%d ",work()); 59 } 60 return 0; 61 }