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MinDistanceProblem.java
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193 lines (108 loc) · 3.15 KB
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public class MinDistanceProblem{
public static int minDis1(int[][] arr,int startR,int startC){
return arr[startR][startC]+process1(arr,startR,startC);
}
public static int process1(int[][] arr,int curR,int curC){
if(curR == arr.length-1 && curC == arr[0].length-1){
return 0;
}
int ans=0;
//到最后一行，只能往右走
if(curR== arr.length-1 && curC < arr[0].length-1){
ans+= arr[curR][curC+1]+process1(arr,curR,curC+1);
}
//到最后一列，只能往下走
else if(curR< arr.length-1 && curC == arr[0].length-1){
ans+= arr[curR+1][curC]+process1(arr,curR+1,curC);
}else{
ans += Math.min(arr[curR+1][curC]+process1(arr,curR+1,curC),
arr[curR][curC+1]+process1(arr,curR,curC+1));
}
return ans;
}
public static int minDis2(int[][] arr,int startR,int startC){
int N = arr.length;
int M = arr[0].length;
int[][] dp = new int[N][M];
for (int i=0; i<N; i++) {
for (int j=0; j<M; j++) {
dp[i][j] = -1;
}
}
return arr[startR][startC]+process2(arr,startR,startC,dp);
}
public static int process2(int[][] arr,int curR,int curC,int[][] dp){
if(curR == arr.length-1 && curC == arr[0].length-1){
return 0;
}
if(dp[curR][curC]!=-1){
return dp[curR][curC];
}
int ans=0;
//到最后一行，只能往右走
if(curR== arr.length-1 && curC < arr[0].length-1){
ans+= arr[curR][curC+1]+process2(arr,curR,curC+1,dp);
}
//到最后一列，只能往下走
else if(curR< arr.length-1 && curC == arr[0].length-1){
ans+= arr[curR+1][curC]+process2(arr,curR+1,curC,dp);
}else{
ans += Math.min(arr[curR+1][curC]+process2(arr,curR+1,curC,dp),
arr[curR][curC+1]+process2(arr,curR,curC+1,dp));
}
dp[curR][curC]=ans;
return ans;
}
public static int minDis3(int[][] arr,int startR,int startC){
int N = arr.length;
int M = arr[0].length;
int[][] dp = new int[N][M];
dp[startR][startC] = arr[startR][startC];
for (int i=startC+1; i<N;i++ ) {
dp[startR][i] = arr[startR][i]+dp[startR][i-1];
}
for (int i=startR+1; i<N;i++ ) {
dp[i][startC] = arr[i][startC]+dp[i-1][startC];
}
for (int i=startR+1; i<N; i++) {
for (int j=startC+1; j<M; j++) {
dp[i][j] = Math.min(dp[i-1][j],dp[i][j-1])+arr[i][j];
}
}
return dp[N-1][M-1];
}
public static int minDis4(int[][] arr,int startR,int startC){
int N = arr.length;
int M = arr[0].length;
int[] dp = new int[M];
dp[startC] = arr[startR][startC];
for (int i=startC+1; i<M;i++ ) {
dp[i] = arr[startR][i]+dp[i-1];
}
for (int i=startR+1; i<N; i++) {
for (int j=startC; j<M; j++) {
if(j ==startC){
dp[j] = dp[j]+arr[i][j];
}else{
dp[j] = Math.min(dp[j],dp[j-1])+arr[i][j];
}
}
}
return dp[M-1];
}
public static void main(String[] args){
int[][] arr=new int[][]{
{1, 30, 100,100,100},
{40, 100,100,100,100},
{110,100,100,100,100},
{1, 100,100,100,100},
{1, 1, 1, 1, 1}
};
int i=0;
int j=4;
System.out.println("Min = "+minDis1(arr,i,j));
System.out.println("Min = "+minDis2(arr,i,j));
System.out.println("Min = "+minDis3(arr,i,j));
System.out.println("Min = "+minDis4(arr,i,j));
}
}