Linearization of the kernel functions in SVM
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 2239 Accepted Submission(s): 599
Problem Description
SVM(Support Vector Machine)is an important classification tool, which has a wide range of applications in cluster analysis, community division and so on. SVM The kernel functions used in SVM have many forms. Here we only discuss the
function of the form f(x,y,z) = ax^2 + by^2 + cy^2 + dxy + eyz + fzx + gx + hy + iz + j. By introducing new variables p, q, r, u, v, w, the linearization of the function f(x,y,z) is realized by setting the correspondence x^2
<-> p, y^2 <-> q, z^2 <-> r, xy
<-> u, yz <-> v, zx <-> w and the function f(x,y,z) = ax^2 + by^2 + cy^2 + dxy + eyz + fzx + gx + hy + iz + j can be written as g(p,q,r,u,v,w,x,y,z) = ap + bq + cr + du + ev + fw + gx + hy + iz + j, which is
a linear function with 9 variables.
Now your task is to write a program to change f into g.
Input
The input of the first line is an integer T, which is the number of test data (T<120). Then T data follows. For each data, there are 10 integer numbers on one line, which are the coefficients and constant a, b, c, d, e, f, g, h, i,
j of the function f(x,y,z) = ax^2 + by^2 + cy^2 + dxy + eyz + fzx + gx + hy + iz + j.
Output
For each input function, print its correspondent linear function with 9 variables in conventional way on one line.
Sample Input
2
0 46 3 4 -5 -22 -8 -32 24 27
2 31 -5 0 0 12 0 0 -49 12
Sample Output
46q+3r+4u-5v-22w-8x-32y+24z+27
2p+31q-5r+12w-49z+12
Source
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主要是好多细节需要考虑:1. 对于第一个输出的正数的正号是否要输出; 2. 系数为 1或 -1的情况;3 . 0的处理(如果系数都为0,要输出最后一位的0)
#include<stdio.h>
char s[10]={'p','q','r','u','v','w','x','y','z'};
int main(){
int t;
scanf("%d",&t);
while(t--){
int a,k=0;
for(int i=0;i<9;++i){
scanf("%d",&a);
if(a==0) continue;
//else k++;
if(a==1||a==-1) {
if(a==1&&k) printf("+");
//else if(a==1&&k==0) ;
else if(a==-1)printf("-");
printf("%c",s[i]); k++;
continue;
}
if(a>0&&k) printf("+");
printf("%d",a);
printf("%c",s[i]);
k++;
}
scanf("%d",&a);
if(a==1||a==-1) {
if(a==1&&k==0) printf("1");
else if(a==1&&k) printf("+1");
else if(a==-1)printf("-1");
printf("\n");
//continue;
}
else {
if(a==0){
if(k==0) printf("0\n");
else printf("\n");
continue;
}
if(a>0&&k) printf("+");
printf("%d",a);
printf("\n");
}
}
return 0;
}
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hdoj-2095-Linearization of the kernel functions in SVM
原文:http://blog.csdn.net/qq_18062811/article/details/47613205