POJ 1163（数字三角形）
Description
7 3 8 8 1 0 2 7 4 4 4 5 2 6 5
(Figure 1) Figure 1 shows a number triangle. Write a program that calculates the highest sum of numbers passed on a route that starts at the top and ends somewhere on the base. Each step can go either diagonally down to the left or diagonally down to the right. Input
Your program is to read from standard input. The first line contains one integer N: the number of rows in the triangle. The following N lines describe the data of the triangle. The number of rows in the triangle is > 1 but <= 100. The numbers in the triangle, all integers, are between 0 and 99. Output
Your program is to write to standard output. The highest sum is written as an integer. Sample Input
5 7 3 8 8 1 0 2 7 4 4 4 5 2 6 5
Sample Output
30
递归版本的AC代码如下：
import java.util.Scanner;
public class Main {
static int[][] D = new int[101][101];
static int[][] maxsum = new int[101][101];
static int N;
public static int MaxSum(int i,int j){
if ( maxsum[i][j] != -1){
return maxsum[i][j];
}
if ( i == N ){
maxsum[i][j] = D[i][j];
}else{
int x = MaxSum(i+1, j);
int y = MaxSum(i+1, j+1);
maxsum[i][j] = max(x,y)+D[i][j];
}
return maxsum[i][j];
}
public static int max(int a , int b){
return (a > b)?a:b;
}
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in = new Scanner(System.in);
N = in.nextInt();
for ( int i = 1 ; i <= N ; i++){
for ( int j = 1 ; j <= i ; j++){
D[i][j] = in.nextInt();
maxsum[i][j] = -1;
}
}
System.out.print(MaxSum(1, 1));
in.close();
}
}递归版本的AC代码：
import java.util.Scanner;
public class Main {
static int[][] D = new int[101][101];
static int N;
public static int MaxSum(){
for ( int i1 = N-1 ; i1 >= 1 ; i1--){
for ( int j1 = 1 ; j1 <= i1 ; j1++){
D[N][j1] = max(D[N][j1],D[N][j1+1]) + D[i1][j1];
}
}
return D[N][1];
}
public static int max(int a , int b){
return (a > b)?a:b;
}
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in = new Scanner(System.in);
N = in.nextInt();
for ( int i = 1 ; i <= N ; i++){
for ( int j = 1 ; j <= i ; j++){
D[i][j] = in.nextInt();
}
}
System.out.print(MaxSum());
in.close();
}
}