A http://codeforces.com/contest/479/problem/A
枚举情况
1 #include<cstdio> 2 #include<algorithm> 3 using namespace std; 4 int main(){ 5 int a,b,c; 6 while(~scanf("%d%d%d",&a,&b,&c)){ 7 int ans=0; 8 ans=max(ans,a+b+c); 9 ans=max(ans,a*b*c); 10 ans=max(ans,a*b+c); 11 ans=max(ans,a+b*c); 12 ans=max(ans,(a+b)*c); 13 ans=max(ans,a*(b+c)); 14 printf("%d ",ans); 15 } 16 return 0; 17 }
B http://codeforces.com/contest/479/problem/B
暴力，每次拿一个，然后排序。
1 #include<cstdio> 2 #include<algorithm> 3 #include<vector> 4 using namespace std; 5 const int inf=0x3f3f3f3f; 6 struct G{ 7 int val,id; 8 friend bool operator <(const G &a,const G &b){ 9 return a.val<b.val; 10 } 11 }g[128]; 12 struct A{ 13 int x,y; 14 }now; 15 vector<A> ans; 16 int main(){ 17 int n,k; 18 while(~scanf("%d%d",&n,&k)){ 19 int big=0,sma=inf,cha; 20 for(int i=0;i<n;i++){ 21 scanf("%d",&g[i].val); 22 g[i].id=i+1; 23 big=max(big,g[i].val); 24 sma=min(sma,g[i].val); 25 } 26 cha=big-sma; 27 ans.clear(); 28 while(k--&&cha){ 29 sort(g,g+n); 30 g[0].val++; 31 g[n-1].val--; 32 big=0; 33 sma=inf; 34 for(int i=0;i<n;i++){ 35 big=max(big,g[i].val); 36 sma=min(sma,g[i].val); 37 } 38 if(big-sma>cha) break; 39 cha=big-sma; 40 now.x=g[n-1].id; 41 now.y=g[0].id; 42 ans.push_back(now); 43 } 44 printf("%d %d ",cha,ans.size()); 45 int len=ans.size(); 46 for(int i=0;i<len;i++){ 47 printf("%d %d ",ans[i].x,ans[i].y); 48 } 49 } 50 return 0; 51 }
c
贪心
1 #include<cstdio> 2 #include<algorithm> 3 using namespace std; 4 const int M=5010; 5 struct G{ 6 int a,b; 7 friend bool operator <(const G &a,const G &b){ 8 return a.a<b.a; 9 } 10 }g[M]; 11 int main(){ 12 int n; 13 while(~scanf("%d",&n)){ 14 for(int i=0;i<n;i++){ 15 scanf("%d%d",&g[i].a,&g[i].b); 16 } 17 sort(g,g+n); 18 int now=0; 19 for(int i=0;i<n;){ 20 int s=i,t; 21 int big=0; 22 int sma=0x3f3f3f3f; 23 for(int j=i;j<n;j++){ 24 if(g[i].a==g[j].a){ 25 t=j; 26 big=max(big,g[j].b); 27 sma=min(sma,g[j].b); 28 } 29 else{ 30 break; 31 } 32 } 33 if(big<g[i].a&&sma>=now){ 34 now=big; 35 } 36 else{ 37 now=g[i].a; 38 } 39 i=t+1; 40 } 41 printf("%d ",now); 42 } 43 return 0; 44 }
d
map 判断是否存在
1 #include<cstdio> 2 #include<map> 3 using namespace std; 4 const int M=1e5+10; 5 int a[M]; 6 int l; 7 map<int,bool> mp; 8 bool has(int x,int y) { 9 if(mp[x+y]||mp[x-y]) return true; 10 return false; 11 } 12 bool in(int x) { 13 if(x>=0&&x<=l) return true; 14 return false; 15 } 16 int main() { 17 int n,x,y; 18 while(~scanf("%d%d%d%d",&n,&l,&x,&y)) { 19 mp.clear(); 20 for(int i=0; i<n; i++) { 21 scanf("%d",&a[i]); 22 mp[a[i]]=true; 23 } 24 bool fx=false,fy=false; 25 for(int i=0; i<n; i++) { 26 if(has(a[i],x)) { 27 fx=true; 28 } 29 if(has(a[i],y)) { 30 fy=true; 31 } 32 } 33 if(fx&&fy) { 34 puts("0"); 35 continue; 36 } 37 if(!fx&&fy) { 38 puts("1"); 39 printf("%d ",x); 40 continue; 41 } 42 if(fx&&!fy) { 43 puts("1"); 44 printf("%d ",y); 45 continue; 46 } 47 int ans=-1; 48 for(int i=0; i<n; i++) { 49 if(in(a[i]-x)&&has(a[i]-x,y)) { 50 ans=a[i]-x; 51 break; 52 } 53 if(in(a[i]+x)&&has(a[i]+x,y)) { 54 ans=a[i]+x; 55 break; 56 } 57 if(in(a[i]-y)&&has(a[i]-y,x)) { 58 ans=a[i]-y; 59 break; 60 } 61 if(in(a[i]+y)&&has(a[i]+y,x)) { 62 ans=a[i]+y; 63 break; 64 } 65 } 66 if(ans!=-1) { 67 puts("1"); 68 printf("%d ",ans); 69 } else { 70 puts("2"); 71 printf("%d %d ",x,y); 72 } 73 } 74 return 0; 75 }
end